Mac OS X 10.4 Tiger Incompatibilities and Workarounds
An impressively long list of all the things Tiger breaks. Microsoft has always envied Apple's ability to break sofware without being screamed at, but it probably doesn't help Apple's market share.
I will probably end up starting with 10.4.2 (should be out soon), but I won't do serious work on my new Tiger machine until 10.4.3. Until then I'll stick with my old G3 and 10.3.9.