According to this screen shot, the Mac Pro will become available in 4 or 8 cores sometime soon. This leak was from the Apple UK store. Hopefully it isn't photoshopped...it would be very easy to fake it. I predict that the new line-up will be 2x2.66 GHz Xeon for $2200, 2x3.0 GHz Xeon for $2500, and 4x3.0 GHz Xeon for $3300. However, the Mac Pro doesn't have space for 4 processors, and I don't know of any new 4-Core inel processors, so maybe the Mac Pro will get the new design that everyone and their mother have been talking about.
UPDATE: I have just been informed that the day that this article was written, intel released a quad-core chip, however, it is not powerful enough for the Mac Pro.