http://www.zdnet.com/blog/microsoft/windows-7-tablets-with-15-percent-market-share-and-other-microsoft-news-of-the-week/11743
Assuming approximately 1mln PlayBook units sold, vs 400k Windows 7 tablets at 1.5% market share, the PlayBook would have 2.5x the share, or 3.5% market share.
:-D