Firewire 2 (1394b) Evidence
While widely suspected, Firewire 2 ports were indeed designed/evaluated for the most recent PowerMac design that was released in August. This is based on an Apple design PDF which was unintentionally exposed on Apple's servers. The PDF was quickly removed.
1394b (or Firewire 2) was approved this year in March, however, due to the lag time before finalization it was not expected until late summer at the earliest.
For whatever reasons, Firewire 2 did not make its way into the most recent revisions. This, however, does seem to indicate that Firewire 2 will be coming soon.