The big table of compatability is here: MobileHTML5.org (Download Screenshot of Full Table Here)
This osX debugging tool is worth a look: iWebInspector.com
Boilerplate cross-platform code is key and can be found here: html5Boilerplate.com/mobile
A bit more about implementing HTML 5 for mobile is here at Wikipedia.
A typographic, designological, visulicious extravaganza!