Some people didn't like BioShock's ending. It was constricting, people complained. Maybe you didn't, maybe you did. But for better or worse, rest assured the Xbox 360's ending will be the same as the PS3's. According to PS3 version's senior producer, Melissa Miller:
When you get a chance to work on something that was really creative you get the temptation to re-do things...We chose not to.
That means that the PS3 version will have the same final hours that the Xbox 360 does. Of course, developer 2K Marin is adding extra features to BioShock PS3, but the grist of the game is still the same. Mmmm grist.