When Apple began taking preorders for the redesigned, American-made Mac Pro in late December, pent up demand was such that ship dates for standard configurations quickly slipped from Dec. 30 to February. Stock of build-to-order units were constrained from the outset with ship-by dates quoted as "January."
Since that point, the Mac Pro has been on constant backorder from Apple's own online storefront, though shipping estimates never reached beyond the February time frame. As of Tuesday, however, it appears ship dates are once again sliding for all models, suggesting production has yet to ramp to adequate volumes.
The shortage was first spotted by MacGeneration (via MacWorld), which noted that even standard configuration Mac Pros were showing April ship dates. At the time, the publication reported modified estimates in international markets like China, France, Germany, Japan and the U.K., but the new ship times quickly spread to the U.S and Canada.
Shortly after the first Mac Pro orders arrived, Apple said it was unlikely to see in-store stock until March. That statement may have been optimistic given the Tuesday's updated ship times.
Professional users have been waiting years for Apple to release a revamped Mac Pro and the overall consensus from reviewers has been largely positive. AppleInsider agreed that the black aluminum cylinder was worth the wait, finding it to be the best Mac Apple has ever made.
While Apple may be running low on inventory, authorized resellers like MacMall and Adorama have limited supply of certain configurations as seen in AppleInsider's live Price Guides.