In Basel he announced that he is going to play, but it seems that he has quite a nightmare draw. First Karlovic, then Nalbandian, Berdych/Ferrer, Djokovic/Murray till the final. All hot and in form players. If you look at the seeds Federer's Half seems much tougher than Nadal's. And Federer had no rest. Wouldn't be surprised if he doesn't get that far.
He should play because Paris-Bercy is the only Masters Series event where he wasn't in the final (he hasn't reached even semifinal there!). The draw looks like a "nightmare" but it's only a theory. Karlovic can lose to Verdasco, Nalbandian can do it the same against Moya, etc.