Worldwide media tablet shipments rose by 88.9% on a sequential basis and 303.8% year over year in the second calendar quarter of 2011 (2Q11) to 13.6 million units, according to the International Data Corporation research group (http://www.idc.com).

Based on this strong performance in the second quarter, and an improved outlook for the second half of the year, IDC raised its shipment forecast for 2011 to 62.5 million units, up from a previous projection of 53.5 million units. Worldwide media tablet shipments in the second quarter were driven by continued robust demand for Apple’s iPad 2, which saw shipments reach 9.3 million units, representing a 68.3% share of the worldwide market (up from 65.7% the previous quarter).

Research in Motion entered the media tablet market in 2Q11 with its PlayBook product, grabbing a 4.9% share of the market. Apple’s strength and RIM’s entrance meant bad news for Android-based media tablets, which saw its collective share slip to 26.8%, down from 34.0% the previous quarter.

Looking forward to the second half of 2011, IDC expects Android to cede additional market share in 3Q11 (dropping to 23%) before it starts growing its share again in 4Q11 (increasing to 25.9%) and beyond. In addition to continued demand for iPads, IDC expects many consumers who were on the fence about buying a media tablet to scoop up US$99 TouchPads as a result of HP’s decision to end production of its tablet product.

IDC expects close to a million TouchPads to ship into the channel before the end of the year. As a result, WebOS’s worldwide market share is forecast to reach 4.7% in 3Q11. However, with no clear plan to license or sell the OS to other vendors, IDC expects the WebOS market share to shrink back to zero by 1Q12.

“Media tablet shipments grew at a solid pace in the second quarter, led by continued strong demand for Apple products,” says Tom Mainelli, research director, Mobile Connected Devices. “We expect shipment totals to continue to grow in the third and fourth quarter, as additional vendors introduce more price-competitive Android products into the market and Apple works to maintain its dominance in the category.”

“Apple’s iOS share will continue to lead by more than 40 percentage points over Google’s Android for the remainder of the year, but we expect Apple’s share to fall closer to 50% by the end of the forecast period as manufacturers bring new tablets to market,” adds Jennifer Song, research analyst, Worldwide Trackers.