Here's the official Adobe response:
http://kb2.adobe.com/cps/834/cpsid_83499.htmlWhen an Apple is produced, the system serial number is flashed onto a chip on the logic board. When your logic board is replaced by Apple (as mine was when I first bought it, because of a faulty Airport card connector), they sometimes don't flash your serial number onto the new board. If this happens, the system identifies your serial number as being "Serial Number SystemSerialNumb". As far as most software is concerned, that's not a big deal at all. But Adobe does all these little cross-checks with serial numbers and MAC addresses and other such nonsense, in order to prevent piracy and license fraud. And so it does care what's in that space. Now, for some reason, 10.6.3 adds some non-alphanumeric characters to the representation of the serial number, which causes Adobe's check to fail. It's a pretty stupid bug, and Adobe blames it on Apple and Apple blames it on Adobe. Probably has more to do with the intrigue between the companies than it does with API compliance and lazy compatibility.
Probably the reason there hasn't been a lot of noise about this bug is that it only occurs with 10.6.3, CS3, and a Mac whose logic board doesn't have a serial number flashed to it - a fairly rare combination. Honestly, you can't blame them for not including this scenario in their test strategy. It's unlikely that a patch for CS3 will be released, because CS5 just came out, and Apple insists that it has done nothing wrong. Well, so it goes.