There's a pretty good thread here you might want to check out. People are putting together an OS X programming FAQ:
<http://forums.macnn.com/cgi-bin/Forum34/HTML/000609.html>
For dev environments, if you're a VB kind of guy, check out RealBASIC. It's a great IDE and lets you build apps for Classic, OS X, and Windows. <http://www.realbasic.com/>
If you want to do some more down 'n' dirty coding in C/C++, CodeWarrior's pretty much the de facto standard. <http://www.metrowerks.com>
Good luck...