Smartango

Symbian Series 60 SDK from forum.nokia.com

Symbian UIQ SDK from developer.sonyericsson.com

Maemo SDK from maemo.org (Nokia N770, N800 tablet pc)

J2ME from java.sun.com

DevRocket from Montavista

OpenMoko from OpenMoko (also mokomakefile project, sdk for linux)

Google Android from code.google.com/android/

BlackBerry JDE (RIM Java Development Environment)