Everything targeted at Flash Player 9.xx.xx will work on N900. So, Flash CS3 & earlier and Flex 3.4 and earlier (tho 3.4 adds some stuff that might not work in 9.xx.xx). If the target base is Flash 9 (fourth byte of any swf - 0x09) it will work on N900, and some even targeted at Flash 10, if not using internal 3D transitions, new typography and couple of added features, should work as well.