If you were looking forward to a shiny new Mac Pro sitting on your desk, you're in for a bit of a wait.
Courtesy of Apple
If you ordered either of the standard 4-core or 6-core Mac Pro configurations, the expected shipping dates have been pushed out to March. Apple usually provides shipping estimates by a number of days or weeks. In this case, Apple is unable to pin down the shipping date to anything closer than March. I wouldn't get my hopes up that the estimate means early March.
Custom configurations usually have even longer ship dates, but at least for the moment, they also have March delivery time frames.
This indicates to me that at least for the time being, the extended delivery dates aren't being caused by specific part shortages but by high demand putting pressure on Apple's supply chain beyond what Apple had originally forecast.
I expect the extended shipping dates to be short term and to clear up by early spring.