IPhone 4 | TechRadar front page: 31s 3G 13s wi-fi | BBC news 28s 3G 10s wi-fi | Flickr photostream page 26s* 3G 7s Wi-Fi |
Nexus One Froyo | 31s 3G 18s wifi | 11s 3G 8s wi-fi | 10s 3G 11s Wi-Fi |
Windows Phone 7 | 30s 3G Wi-Fi 15s | 17s 3G 12s Wi-Fi | 7s8 3G 9s Wi-Fi |
*yes really, yes, repeatably.

You can read my in-depth, at-length review over at TechRadar; I have caveats but I'm impressed with what I've seen so far. There are drawbacks (every mobile OS has flaws today) and I need to see how it handles as a main phone over time when I have a handset for long enough to do that, but I'm impressed with what Microsoft delivered in the time they had. Now they have to keep up the pace.