your crunchy tech l'inq says that the problem was on facebook's end and other browsers were experiencing this too (i don't know why the INQ chose to blame only chrome):

"Looks like this is more of a problem on Facebook’s end than a browser-related issue. We’ve seen phishing scams targeting Facebook users in the past, on multiple occasions, but this is something completely different.

It could have something to do with Facebook Connect (which they just started rolling out with a bunch of launch partners), anyone have any good theories about that?

Update 4: the issue is topic of discussion in the Facebook Developer Forums (here and here). An administrator acknowledges that fbcdn.net was listed as a phishing site but that the problem has now been resolved, yet I’m still getting the warning message.

Update 5: problem appeared to have occured due to a bad advertisement link. The issue has now been resolved."