No, it's not a sequel to the Hollywood thriller that takes place in a parking garage.
P2: The Unforgiven is a sequel to a film called P, a horror thriller about a young woman -- a Bangkok go-go dancer -- with black-magic powers.
Directed by Paul Spurrier, P had a good reception when it was shown back in 2005 at the New York Asian Film Festival, the Brussels Fantastic Film Festival and the Yarmouth Film Festival. It's never been released in Thailand, and I have yet to actually see the movie.
MonteCristo International is shooting the sequel now, though few details have been revealed. Perhaps I'll get the chance to ask Paul about this the next time I see him.
(Via Film Stalker and Bloody Disgusting)