I found out today that 10.5.3 breaks StarCraft :( Basically, after installing 10.5.3 if you launch StarCraft it will show the initial configuration dialogue but then crash back to the desktop.
Apparently the reason for this is that StarCraft tries to switch to 256 colour mode but this was disabled by Apple in the latest update, so the game simply crashes.
So far neither Blizzard nor Apple has published a fix, what was disappointing though is that neither of the companies has published this information on their websites. For example I downloaded StarCraft from the Blizzard store and after a 2 hour download, it installed fine but obviously wouldnt launch. No where though on their site do they state it doesnt work with 10.5.3.
This supposedly also impacts Diablo II as well but I havent had an opportunity to test this.
Lets hope that they fix this soon and in the meantime, please consider letting Apple and Blizzard know that they should fix this!