An anonymous source provided the following specs for upcoming PowerMac G4's... presumably at MWNY.
1.0 GHz, 1.2 GHz, and dual-1.4 GHz G4's
DDR 333 MHZ
ATA 133 support
4 64 bit PCI
1 AGP
Gigabit Ethernet, Firewire, USB
60, 80, and 120 GB drives
New Superdrive, and faster CDRW.
Built-in Bluetooth
$1599, $2299, and $3299.
These certainly sound like reasonable specs for future machines... again, the upcoming Servers (May 14) specs may help confirm/deny some of these specs.