It is difficult to say if this is a good or bad statistic, but 4 months after the release of the OS it appears around 1% of bloggers are using Windows Phone 7, if tweet stats from South by South West is any indication.
According to stats by DigitalTrends, who counted tweets originating from this Interactive Media festival, the market share by OS had 74 percent of #SXSW tweets originating on an iPhone (60 percent) or iPad (14 percent). Googleâ€™s Android OS matches the iPad usage stat at 14 percent, trailed by BlackBerry (12 percent) and Windows Phone (1 percent).
It is unlikely that the numbers represent the real market share of Windows phone 7, which may be more or less, but it suggests you only have a 1% chance of running into an blogger informed about the OS by actual use.
See the rest of the stats at Digitaltrends here.