Ok.. I'm a newbie still waiting on my arduino to arrive. In the meanwhile, i've use the IDE and kinda love it. Now I wanna contribute too. I always wanted to develop a gui based programming tool (Something like the NXT which i'm preoccupied with!) and now i'm thinking why not something like that for arduino 
But i have no clue where to start.. Any suggestions??? Well i can code to some extent in C, Visual Basic & Java but have not done any serious application development for a long time(have almost forgotten it!)
Arduino is supported under several OS, Java is perhaps a good choice isn't it?