Appleinsider provides some vague notes about the upcoming PowerMac and PowerBook updates.
According to the rumor site, PowerMac and PowerBook updates are reportedly delayed until late March and late April, respectively. Specs for the upcoming revisions are unclear, but Appleinsider points to ATI video card supplies as a possible reason for the delay.
Meanwhile, according to an unverified MacRumors source, the PowerMac G5 delays are reportedly related to difficulties with cooling in the faster machines.
While no specifics are available, one would assume that Apple will be using the new PowerPC 970FX in upcoming PowerMac revisions. The 90nm chip should run cooler than its 130nm counterpart.