This is a rant covering the design and usability portion of the post rating controls on the forum. If you're not interested in these things you may find this post boring but it does provide some insight into the whole though process that takes place when doing usability analysis on a piece of software or design.
I recently wanted to rate a post higher and instinctively my hand went to the rightmost icon and clicked, thus hitting the minus rating instead of the plus one.
This made me think about the way we usually visualize things increasing, and that is, moving towards the right on a scale: think of the x axis, what's on the right is larger than what's on the left, or the way you increase intensity by turning a knob clockwise (towards the right). Considering this approach humans take the symbols should be inverted, with the - on the left and the + to the right of it.
The other thing we have to take into account is the fact that most people read from the left to the right; this means that placing the positive rating towards the left influences the user to high-rate a post rather than low-rate it, or better said, implies that it is easier to high rate a post and that it's better to take some time to consider if you really want to low rate it.
Now, the drawback to this point of view is muscle memory: people actively go towards the right when they expect something to increase (thus going to hover over the minus symbol more often than on the plus one when they really want to high-rate something); this is coupled with the fact that the "toolbar" isn't always visible (thus enforcing the reading from left to right part) which in turn makes it so that when you want to rapidly high rate something the chances of hitting the minus symbol increase.
A positive aspect on the back-end implementation is that a vote is not definitive and you can high-rate it after noticing the mistake. The drawback is that you can't bring your rating back to neutral but that is somewhat mitigated by the fact that you initially wanted to rate the post so you'd have no reason to go back to a default rating except for the case when you accidentally clicked on the button (action which is minimized by the distance from the reply button and the fact that the controls only appear when the "toolbar" is hovered).
So that's it, hope you'll find this interesting enough. I'd also love to hear your opinions on this topic.

Slightly false, they appear when the post is hovered over.
I have not seen any problem other than that the icons/buttons are a bit too small and as such may be hard to hit with shaky hands.

Yeah, I forgot about that. Thanks for pointing it out.
I didn't want to come out as pointing problems, just showing how a usability analysis might look like and the train of thought involved in it.

Except you're dealing with a binary distinction here, rather than a scale. Good / Bad, On / Off, Up / Down, Yes / No, Plus / Minus. I suspect (in English anyway) that in these cases, you usually find the positive option listed first.
I'd be more suspicious of the red/green colour scheme.

Well, red means "stop", green means "go". So red means "Stop posting" and green means "keep posting". Problem solved :P
Plus, "Plus or Minus", so it makes sense to be in that order.

I'm fine with the current button layout, but I do miss the option to remove a vote. It's happened at least twice that I was going to quote someone and ended up giving them a vote instead, and then you suddenly have to decide if a completely average post weighs more towards the positive or the negative end of the scale.

You don't get much frags, do you? ;)

Yes, but that still works enough for traffic lights and the like :p

Yes, but the actual buttons are marked with the plus and minus symbol so they can't be confused; if they weren't then that would of been indeed a problem.
The green light is tinted blue so even if you can't differentiate from green to red you'll see the blue haze; besides this, the position to the green relative to the red is always the same, red on top, green on bottom.

I to have accidentally hit the wrong button. Maybe a little message saying "Are you sure you wish to give this post a negative/positive rating" would help. It doesn't really annoy me though.

An interesting conundrum: if you were to place the buttons below each other, where should you place the green button? On the bottom, because that would be similar to traffic lights? Or on top, because you'd expect a + there?
Of course, the most logical solution for accidentally pressing the negative or positive button would be if you could compensate your mistake by being able to press the opposite button twice. First to get it back to neutral and the second time to give the post the score you actually want.
I wonder why I've never encountered a comment rating system that was implemented like that.

I'm glad I'm not the only one who has thought about this.