The tablet market grew 49.5% year over year in 3Q12 and 6.7% over the second quarter of 2012. Android shipments, led by Samsung and Amazon, surged during the quarter, at the expense of Apple, which saw its share slip notably during the quarter.

"After a very strong second quarter, Apple saw growth slow as both consumer and commercial (including education) shipments declined, and rumors of a forthcoming iPad mini began to heat up," said Tom Mainelli, research director, Tablets at IDC. "We believe a sizeable percentage of consumers interested in buying an Apple tablet sat out the third quarter in anticipation of an announcement about the new iPad mini. Now that the new mini, and a fourth-generation full-sized iPad, are both shipping we expect Apple to have a very good quarter. However, we believe the mini's relatively high $329 starting price leaves plenty of room for Android vendors to build upon the success they achieved in the third quarter."

Apple's slowdown put a sizeable dent in the company's commanding worldwide market tablet share, which slipped from 65.5% in 2Q12 to 50.4% in 3Q12. The company shipped 14 million tablets in the third quarter, growing 26.1% year-on-year.

The remaining top five tablet vendors all gained share during the quarter as a result. Most notable was the impressive quarter turned out by Samsung—driven by its Galaxy Tab and Note 10.1. Samsung shipped 5.1 million tablets worldwide in 3Q12, up 115.0% from 2Q12; that's an increase of 325.0% from 3Q11, when it shipped 1.2 million tablets.

The top 5 was rounded out by Amazon, ASUS, and Lenovo; with all three vendors experiencing sequential growth over 2Q12 while Lenovo and ASUS also saw solid year-over-year growth. Amazon, which did not have product in 3Q11, announced new 7-inch and 8.9-inch Kindle Fire HD tablets late in the quarter, and began shipping the new 7-inch HD version (in addition to a refreshed version of the original 7-inch Fire) in mid-September. This helped grow its worldwide market share from 4.8% in 2Q12 to 9.0% in 3Q12, despite only shipping in the U.S. (the company began shipping into five additional countries in 4Q12). The company shipped 2.5 million tablets in third quarter of 2012.

ASUS' share growth was backed by strong shipments of its Google-branded Nexus 7 device; Lenovo's gains were driven by strong shipments in China. The company sold 2.4 million tablets in 3Q2012, which rose by 242.9% year-on-year. Its market share made up 8.6%.

Lenovo’s share in the market made up 1.4%, after it sold 400,000 tablets in the third quarter of 2012. The growth of sales made up 100% year-on-year.

"Samsung took advantage of an opportunity in the second quarter," said Ryan Reith, program manager, IDC's Mobile Device Trackers. "The company offers a wide range of tablet offerings across multiple screen sizes and colors, and that clearly resonated with more buyers this quarter. Its growth to 18.4% of worldwide market share during the quarter represents the first time a competitor has attained this level of share since the original launch of the iPad."

"Competitors are turning up the pressure on market leader Apple," Reith added. "With the recent introduction of a number of Windows 8 and Windows RT tablets, consumers now have a third viable tablet platform from which to choose. However, price points are critical in tablets, and Microsoft and its partners will have a tough time winning a share of consumer wallet with price points starting at $500."