I've been looking for a waterproof P&S too. I thought about the new Canon one (Powershot D10), but it is still not available.
I do like the P&S + UW housing idea.
This one, Canon Powershot SX230 IS looks interesting because it has 14x zoom and GPS recording capability. Total for cam and Canon housing about $520. But, I don't think it has manual settings? It has an Ikelite housing but also a Canon housing for a lot less $$$. The Ikelite has ability to attach a strobe, so maybe that makes the difference? Or maybe it is just a better housing? I need to read more.
I read more. It does have full manual setting. Sounds pretty good.