Game has been revoked?

Can you contact the gift-er and see what's happen at their end? It doesn't look good.

Huh … I guess the next step to send a (politely worded) support ticket to steam asking why your gifted copy was removed.

Most probably something went wrong with the gifter's purchase. Ask him to see if his e-mail has something about the billing.

Maybe the gifter bought it with a credit card in wrong status (it wasn't his credit card, or stolen?) and that way you haven't now the gift :S

I believe steam has been having gift issues all day.

Did he email the gift to you and you redeemed it, showed up in your library and then was later revoked?

Sometimes I get a message that the game has been revoked, even though it adds the game to my list. Usually this happens when lag causes Steam to think I've accepted the same game twice.

Check your games list.