Compatibiliy Issues You Have Seen

I've been in the process of porting my game code over from PPC2002 to PPC2003, and it got me thinking about the quirky compatibility problems that could pop up. I was thinking that maybe we could all share little bits of port-over advice...any problems we have seen in porting from 2002 to 2003 or even device-specific problems.
I figure its better to hear about them in advance than have weird problems down the line that may or may not be related to the code. :)
I figure its better to hear about them in advance than have weird problems down the line that may or may not be related to the code. :)