According to NPD, Apple shipped 17.2 million mobile PCs* worldwide during the first quarter of 2012, enough to capture a 22.5 percent share of the market — more than double that of its closest rival, Hewlett-Packard. During the same period, HP shipped just 8.9 million mobile PCs for an 11.6 percent market share.

How did Apple manage to dominate PC leader HP in the mobile PC market? The iPad.

Of the 17.2 million “mobile PCs” Apple shipped, 13.6 million were iPads. And in that particular segment of the market — tablets — Apple’s domination is unrelenting. In the first quarter, Apple claimed a stunning 62.8 percent share of the tablet market, dwarfing every single one of its rivals. Samsung, its next closest rival, shipped just 1.6 million tablets during the quarter, for a share of 7.5 percent. Amazon followed with 900,000 tablets shipped and a 4 percent share. Bringing up the rear: Research In Motion and Asus, which sold 500,000 tablets each, for a 2.3 percent market share.

*NPD defines mobile PCs as tablets and laptops.

While the mobile computing era was obviously born quite a while back, iSuppli’s report would seem to make its advent official. “This marks a major event in the PC market because it marks the start of the age of the notebook,” said Matthew Wilkins, principal analyst for compute platforms at iSuppli. “The notebook PC is no longer a tool only for the business market, or a computer for the well-off consumer; it’s now a computer for everyone. While the third quarter will be remembered as the time when the scale of the global economic/credit crunch truly became apparent, the PC market managed to deliver strong unit shipment growth during the period.”