To be fair, however, they're not advertising it as a feature that works with all games.
I imagine it's not enabled on all games for two reasons. First, licensing. Can't say for certain, but I figure this plays into it somehow. Second, the Vita is still new - and attach ratio is very important for getting developers to make games for the system (see: Wii). If Vita owners don't pick up any games (because, why bother, if my entire PS3 library is open for play and the Vita lineup is a bit lackluster right now), it would hurt the platform when developers determine if they want to make Vita games.