Yep, the SEA startup scene is in full throttle in the past few months. The recent buyout of Koprol by Yahoo, Octazen by Facebook is definitely a sign.
IMO, you can't go wrong with Manila :)
I'm interested in the Philippines. Is there a startup culture in Manila or Cebu, and what does that look like?
The startup scene in the Philippines is concentrated on Manila. Friendster, Insync, ProudCloud seems to lead the pack. I suggest you mail @terpua since he can introduce to the details.