Basic Scripting - NAB622's Website
In the JA SDK, you'll find "ICARUS Manual.doc" which may give you some insight, and also the source files for scripts used by the JA base maps (so if you've ever wondered how certain things were done in one map or the other, you may find it in there). Likewise the JO SDK contains the source files for scripts used by JO sp maps, which are also quite helpful.
Then there also some scripting tutorials to be found here (for cinematics, objectives, NPC abilities):
KENGO MAPS - Tutorials