I don't use networks like Facebook or Twitter, I only use ICQ and Skype to stay in touch with some friends or former classmates.

Then how do you tell someone I dont want to follow your tweets, status, myspace, whatever they are called. Out of six kids, myself and my brother who is army are the only two not one those sites....
Personally I just dont see how it benifits me to make a status update PFC XYZ died today @0918 from an IED. To let others know what my status is.....
The PFC I mentioned IS NOT I REPEAT NOT DEAD. He did however shit himself.

What do you mean "how do you tell someone I don't want to follow your tweets, status, myspace, whatever they are called"? I just don't follow them, plain and simple and they don't appear in your view.
Why do you have to explicitly explain to them why you don't follow them? It's your personal choice and you don't have to explain yourself to them. If you consider you have to then that's a different issue and you can always resort to the good old "Your updates do not hold any relevant content for me".
As for you not seeing the benefits that's a different part because when you share you don't usually do it expecting something (a benefit) in return; I share an interesting link I find on Twitter because I believe that other people who follow me will find it interesting, I put up a question there because I know I'll get an answer faster than if I would post in on a forum and it'll reach a larger audience than if I would just send it in an email to a friend or coworker.
Nobody says you have to post an update saying "PFC XYZ died today"; you can very well post an update saying "Got to see this great new piece of tech in action. Recoil on it is awesome" or anything you think will be valuable to others that follow you.
It's all about finding value and spreading it. The crap is there but for every crappy tweet there is at least one that has something interesting in it.
As for using IM versus Twitter/Facebook to stay in touch, they're very different systems due to their nature: one is real-time, the other is near-real time.
I may not be online when a friend back home is in order for him to tell me that he wrecked his car or failed an exam but I can sure as hell be able to see his tweet about it when I open my client and send a reply even if we're not both online.
And regarding that soldier that posted that information: it's up to your organization to set and enforce it's privacy rules. You can't blame a service for allowing anyone to post anything but you can blame the person for posting that crap despite knowing that it contravenes the security policies.
For example, in the case of my workplace, we have a very clear disclosure guideline which states what can and can not be released to the general public. We manage a hell of a lot of databases and server clusters and we are allowed for example to tweet that "Yeah, a database is currently down and we're working on it" but we may or may not be allowed to say "It's down because there was a coolant leak that lead to the overheating of the rack and blowing a couple of drives". I might get that as a DM on Twitter because I'm an employee and DBA and need to know what happened so I can fix and work around the limitation (and we use Twitter DMs because it's a free way to send text alerts: all the team is following a master account and has mobile updates turned on and as soon as a tweet is posted on that account everyone is notified).
If I was to release that information to the general public I'd get my ass fired in a second and in a huge fucking lawsuit over disclosing sensitive information.

Not a social network person myself. The GOG forums are about the ONLY place on the net that I do anything remotely resembling social networking.

I log into MSN maybe twice a week, I closed my facebook down in the spring. Best thing I ever did.
Definitely a time waster.

In my experience, leaving important, consequence-ridden decisions in the hands of the average person rarely works. That's why people are so outspoken about "social networking" timewasters, because the dangers are not always known.
I will say that I LOVE using Myspace to listen to new-release albums, but that's not an inherent endorsement of myspace, just legal free access to music.

I only use IRC (... just because there's GoG chan :D ) , IM clients, wave (and I AM impressed by it) and ... that's 'bout it, really :D Oh and forums, of course. This community is still great. Most of my friends have facebook, but I actually hate these kinds of ... Internet 2.0 they called it? Yeah, right.

Then filter the crap out of them if you don't trust your employees; you are at work, only the websites that are considered necessary are available and after hours if you screw up you get screwed, simple as that.
In my experience, leaving important, consequence-ridden decisions in the hands of the uninformed average person rarely works. If he knows he's going to lose his job because of a leak then he will be silent and careful.

I have to agree with this. I'm a new Twitter user, and I was really surprised what could be found. Started as a skeptic, now a frequent twitterer.
That said, Facebook is a no-no. Google Wave is VERY promising for practical uses. Actually, most of my online communication is via Google services these days. Oh, and MSN.

I always saw craigslist as a goods/services type of place and not a social networking place..

You do not feel any obligation to have your family on your list? My little sister is a twit, and her updates are "OH I hope Jake asks me out for coffee..."
Most of the people I deal with on a day to day basis do not use those sites, it has just been in my experiance something that has caused more problems then it has solved. A friend of mine found out his wife was sleeping with strangers via CL, another friend got an update from his wife via CL that she went to some *fucking amazing party and blacked out*. In the example of a person dying it has happened, not even the next of kin was notified before the Next of Kin found out via MySpace that their son was killed in action.
Again, im not saying it is not the sites that are bad just some of the people

From wiki http://en.wikipedia.org/wiki/Social_network
A social network is a social structure made of individuals (or organizations) called "nodes," which are tied (connected) by one or more specific types of interdependency, such as friendship, kinship, financial exchange, dislike, sexual relationships, or relationships of beliefs, knowledge or prestige.
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So, while even GoG is a social network as we gain and or lose rep by our peers. We share some form of basic kinship/friendship with those we choose to communicate with.
It is not the myspace/hi5/beebo/last.fm/facebook sites I dislike it is the idiots on them that cause me to not want to bother.
I'd agree with Number 4) off Delixe's list, however, I can find cool shit via http://www.gog.com/en/forum/general/random_internet_finds_funny_usefull_mindblowing

Real-time? We could use that to send signals back in time!