It is growing fast. It has more than doubled its market share. I don't care how small the actual starting number was, it is still good progress. If you don't think so, go ask Palm!
On a similar note, the rapid Android evolution, I think, might actually be harmful. I have been without a contract for over a year now. I have been wanting an Android phone. However, each time I settle for one, a new and better one rises over the horizon. So I wait. By the time that one comes to market, the pattern is repeated.
Another real interesting story, from this data, is that the iPhone growth has become stagnate. Looks like Apple hit the ceiling! Unless of course they add in iPad sales numbers next year.