Touchscreen: Usability Guidelines

An interesting read, found on google:

http://www.uxalliance.com/fileadmin/user_upload/Touchscreen_Guidelines.pdf

I think they missed a couple of key issues and metrics, but summed up many of them.

And fi you like it, you should also check out the rest of their stuff:

http://www.uxalliance.com/expertise/reports-publications.html