I have just read through the summaries and Apple's Tiger preview page, and I think Apple is finally getting its act together to reach into areas where Windows has been king for almost a decade: Mainly, the fact that along with the newe API's available in Tiger, Core Image, Core Video, 64-bit memory access, ACL's (I understand this will be available on all versions), the new search API etc, there is the fact that XCode 2.0 includes visual modelling of applications. This has been something that has been sorely missing in OSX, as Rational has never thought about porting its tools to OSX and there has been no alternative up until now.
I think it starts to make OSX a very viable alternative to enterprise developers, as XCode is free with the OS and MS's tools cost a fortune.
I think that the Automator and Dashboard applications will also add to the value of the OS, as Automator will be miles above MSTask, and Dashboard will allow the hundreds of people who hate Applescript to finally make useful little widgets for the OS.
Well done Apple. Now, just bring on the G5 Notebooks and I'll be happy.