MacWorld UK has an excellent article about Mac OS X and developer support.
Kerris confirmed that Mac OS X is attracting a new wave of developers. Former Unix, NeXT and Java developers are moving in, and threatening to shake-up the industry.
The article continues with developer testimony about OS X as a development platform, as well as in Production houses and studios... Of note, they report that Sony is considering porting it's in house Unix apps to OS X.