PPK is the owner of the invaluable QuirksMode.org and has been digging into mobile browsers for the last few years – This research produces some quite disappointing results with layers of complexity in browsers that you would expect to have some consistency – “There is no webkit for mobile”
Anyway, he gave a talk recently and has published the slides at http://www.quirksmode.org/blog/archives/2011/03/gomez_webinar_s.html
Some of the data was eye opening for me.
Enjoy!