The tussle for market share among smartphone OS vendors tightened as 2010 ended, according to the latest figures. Apple's iOS led all comers, but Google's Android operating software was not far behind while RIM's Blackberry system sat squarely between them in a statistical dead heat.

November data from The Nielsen Company showed Apple iOS with 28.6 percent of the market, clearly ahead of Android‘s 25.8 percent share. With regard to Blackberry, however, the race was almost too close to call. RIM's offering held 26.1 percent of the market. Taking into account the study's margin of error, that made it statistically tied with both Apple iOS for first place and Android for third place.

The trends were clearer, however. They showed Android making rapid strides at the expense of its rivals. Nearly 41 percent of those who purchased a smartphone in the last six months chose Android, according to Nielsen, well ahead of both Apple at 27 percent and Blackberry at 19 percent. Furthermore, Android has been accelerating the rate at which its new adoptions have been gaining on Apple and RIM, both of which have been essentially flat compared to Google's offering over the last several months.

Overall, smartphones in general are cementing their grip on mobile phone users. During the month of the study, Nielsen reports, 45 percent of recent acquirers chose a smartphone over a feature phone.