It would appear that it is correct or partially correct. I couldn't find data for the whole time, but as of the end of last year, OS X market share appears to have flattened and then gone both up and down from that point by a fairly small amount.

Here is an article talking about market share http://annasoft.wordpress.com/2010/10/04/report-ios-driving-...

and here is one which doesn't mention mobile: http://www.statowl.com/operating_system_market_share_trend.p...