BlackBerry

http://www.blackberry.com/developers/downloads/simulators/index.shtml

Google Android

http://code.googlecom/android/reference/emulator.html

iPhone

http://marketcircle.com/iphoney

Opera Mini

http://www.opera.com/mini/demo

Windows Mobile

http://www.nsbasic.com/ce/info/technotes/TN23.htm