I've been to Manila six times in the past three years and am seriously considering moving there. At the moment, OBar in Ortigas is the best thing going. It's just to the north of the Sitel OJV call center, which you can find on Google Maps. I'd drop by around 1130pm and stick around until about 4am.
Chelu in Malate is also pretty fun, but gets started later, perhaps around 1am. If it's Friday, you may want to drop by Jardin Garden Club at the Remington Hotel in Resorts World Manila (Pasay, near the airport) after 11pm. It's mixed but very friendly. You could also check out House Manila on Saturday, in the basement of the Remington Hotel.
If you're into gogo boys (also called macho dancers), check out White Bird. Be sure to get there before midnight. You'll get an eyeful at about 1230am. Solution (near Libertad) is also very scenic.
Many clubs are mixed and quite gay friendly. Alas, Filipinos are shy so you will often need to make the first move.