Its quite interesting surfing the web from a PDA/Smartphone, just to see who's homepages recognises that you are connecting in from a mobile device.
I took the top 10 most popular websites globally as listed at -
http://www.alexa.com/site/ds/top_500
So here's the results(using Windows Mobile 6 emulator QVGA Landscape, with a locale of English US and set to single column view.
1. Yahoo http://www.yahoo.com
Doesn't look very mobile friendly to me...
2. Microsoft Network (MSN) http://www.msn.com
Wow... Not nice at all..
3. Google http://www.google.com
Hooray... A proper mobile page...
4. YouTube http://www.youtube.com
I don't know whether my luck or design, but this looks pretty mobile friendly..
5. Myspace http://www.myspace.com
Looks good to me...
6. Windows Live http://www.live.com
Phew, a mobile page. However doesn't seem to be branded as Live.
7. Baidu.com www.baidu.com
OK, Baidu is a Chinese search engine (you learn something everyday), so maybe on a Chinese device this will look fantastic. I'll reserve comment.
8. Orkut.com http://www.orkut.com
Looks pretty good to me.
9. QQ.Com www.qq.com
QQ, Chinese focused instant messaging site, looks mobile friendly to me.
10. Wikipedia http://www.wikipedia.com
Hard to tell but on scrolling down didn't appear to be particularly mobile friendly.
I appreciate that lots of the listed companies do have mobile specific url's, i.e mobile.msn.com, but just wondered on first hit to theses popular sites what the user experience would be.
I posted some time back, about a simple bit of code to detect if your at least connecting in with a Windows CE based device to a web page, hint hint offenders above 
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