According to a research report released by Strategy Analytics, Android based smartphones will account for 4% of the market in Q4/2008.  They expect total of 10.5 million smart phones sold during this time, of which 400,000 will be Android based phones.

From the press release: Chris Ambrosio, Executive Director at Strategy Analytics, added:  Google has the brand power in the USA to make a big impact at launch. The main issue will be operator subsidies. As seen with the iPhone and smart devices in general, retail prices need to be well below $200 to be competitive.

Longer-term success will, of course, rest on Android vendor ability to create designs with wow factor and an intuitive user-interface. Google will do its part to drive growth, and we expect Android will eventually offer a compelling range of mobile applications emphasizing Google’s online assets, such as advertising, mapping and search.

IN my opinion, thats pretty optimisic considering that first phone won’t even be available until Sept 23.  I am not sure if the platform is past the stability issues that we have been hearing for some time.  And it is not likely that people will join TMobile only for Android phone. TMobile does not have 3G, so thats a big no-no for several people.