Chitika, a small ad network, has released some data collected over the last 20 days collected from browser ad impressions, and they note Windows Phone 7 already makes up 0.9% of Android impressions and 0.6% of iPhone impressions, from a total of 31.5 million impressions.

While they claim “that number is remaining relatively stable, with very little significant market share growth in WP7” a simple linear regression ( and even just eyeballing the graph) shows a clear upward trend, with Windows phone 7 taking around 0.1% market share of the combined share of its rivals in just 20 days. Of course at that rate it will take 30 years for Microsoft to take 50% market share, but hopefully Microsoft can accelerate it at some point :).

Read the blog post at Chitika here.