hedwards: I'd be more concerned about losing a file due to somebody acquiring a computer with the dropbox install still active, or sitting down and deleting things out of that folder as I don't think Dropbox puts any effort at all into worrying about that.
But, I think that last point is pretty much any provider of such a service, not Dropbox specific.
Arkose: Dropbox has a recycle bin in the cloud (as does Skydrive and probably most other services) allowing recovery of files for up to 30 days. Previous versions of non-deleted files can also be restored depending on the service (e.g. Skydrive only stores previous versions of Office file types).
Which is fine as long as you notice it within that time frame. I don't mess around with services like that any more, but it definitely concerns me that some folks view it as a back up when it's just a convenient way of sharing or synchronizing.
As long as there are backups, then it should just be a minor inconvenience at best..
EDIT: On rereading, I see your point. If you immediately regret your mistake, they do have something to deal with that.