I get at least 24 hours and sometimes 36 hours on every battery charge. Am running Android 2.1 Eclair (mod-ed) on a Huawei. To be honest, I had first thought that for a relatively low-priced made-in-China device, I would get much less battery life. But I guess was wrong on that one.

IMO, I think any phone battery wouldnt even last 12hrs with "heavy" usage. There should be a problem though if it does not last long (say 12hrs) with "light" usage. Now a typical un-modded android OS runs a number of background services like GChat, GMail, Location/GPS (a real battery sucker) all over HSPDA. You might want to manage these. I have never owned a Winmobile so I cant list the background services running on the phone and so I cant really draw an accurate comparison of both OSes on battery life.