Technically, that's not identity theft. That's a phishing scam. Basically, they send you an email that looks like it's from Facebook saying there's some problem with your account, click here to fix it. When you click, you have to log in with your FB username and password. But you're not actually logging into Facebook. You just gave your username and password to the scammer. They then log into your account and mine it for any useful information (friends names, emails, etc) and then scam those people.
It's not unique to Facebook, this sort of thing could happen with your bank account credentials (leading eventually to real identity theft), or your NC4x4 account. The 'stranded friend' scam is as old as the exiled African prince scam, maybe older. Facebucket just makes it easier than ever to execute.
The takeaway is to never click on a link in an email, particularly for a site that needs login credentials. Type out the URL in the browser manually.
