If someone has their processing code available (like the excellent stuff from the free examples by Ira Greenberg and of course stuff from /404/ ben / to mention just a few) and I use it for my application, what are the legal implications of this? If you credit the people used is that enough or does the source for the application also have to be made available? Processing makes it so lovely to slap in new code without any of the usual Java worries, infact I love the "non-OO" approach it seems to encourage, makes life a whole lot easier imho. Couple that with the abundance of source around from talented people and you can find that an app builds very quickly indeed. Processing sure is one of the best "stand on the shoulders of geniuses" initiatives Ive ever come across (since Blitz Basic on Amiga which it reminds me of highly).

My app wont be commercial or used to make money but I will probably put it online in applet format for people to play with (can an applet access the mic btw? i guess it can if its signed). I admire everyone who gives their source away but it can be a painful thing to do sometimes Anyway I thought if I made my app open source it could be a very nice way to get the community involved in its development also.

peace out and keep processing

Unless it is explicitly under a GPL-like license, which forces you to publish your derivative source code, you are probably safe by just giving credit to authors (ie. respecting copyright rules). One might consider that code given on the Net without explicit license is more or less in public domain... IANAL, though.
Giving full credit (names + URLs) would be nice too.