I work for a commercial printer, and we asked ourselves the same question a while back. We started here:
There are links to download official logos there too. (Then came the struggles with clients who wanted to ignore all the rules )
As for the Photoshop Lounge (Lonuge!), it's now call the "Forum Lounge" and it's here:
...but it's not what it once was.
I'd say you should get your client to contractually agree to bear the responsibility for any such infringement.
It really boils down to whether this is fair use (unless Facebook has approved it, of course!). And for that you need to be judge executing a careful 4-part test...
Sweet! Thanks! Doesn't look like there are THAT many rules but I have not read everything on the Logo guidelines page yet.
Yes, the Facebook and Twitter logo's are practically part of any current .indt these days aren't they?