Apple may have topped the US smartphone chart in Q4 2011, thanks to the iPhone 4S, but it needs a revamped iPad if it's to reverse the trend in the tablet market.

According to Strategy Analytics, a market watcher, world tablet shipments topped 26.8m units in the last three months of 2011 - 66.9m in the year as a whole - giving Apple a reduced share of 57.6 per cent, down from 68.2 per cent in Q4 2010.

Of course, back then there was very little in the way of competition. Now, rather more vendors are pushing fondleslabs. You can see that not only in Android's rising market share - up from 29.0 per cent in Q4 2010 to 39.1 per cent in Q4 2011 - but also Microsoft's growing share.

Windows didn't trouble the scorer in the fourth quarter of 2010, but a year on and it was to be found in 1.5 per cent of the tablets that shipped in the three-month period. Microsoft is banking that Windows 8 will boost its tablet market share considerably.

It's worth re-iterating that Apple's iOS is backed by one vendor. Android and Windows have the support of a number of major suppliers. So while Apple shipped 15.4m tablets in Q4 2011, the 10.5m Android alternatives were supplied by Samsung, Asus, Acer, Amazon and more.

And, yes, Amazon's Android-based Kindle Fire is one of the key reasons why the Google OS' share increased. But Apple's CEO, Tim Cook, is broadly right: Apple's tablet shipments leapt ahead irrespective of the alternatives.

But that's no cause for complacency. Apple's unit shipments in Q4 2011 increased 111 per cent year on year, but Android's were up 234 per cent. The market as whole increased 151 per cent.

Full-year shipments totalled 66.9m tablets, up 260 per cent from the 18.6m units that shipped in 2012.

DisplaySearch, another market watcher, recently estimated that 25.2m netbooks shipped in 2011. Ultrabooks, Intel's new hope for securing the consumer computing market in the face of the tablet onslaught, are forecast to reach shipment volumes of around 20m units in 2012. ®