RIM's US marketshare is not 3%.
I can't believe people even believe this, nevermind the arguments going on about the semantics.
You can't say Microsoft has more marketshare cause they sold more phones in one month (that doesn't even sound logical to me), cuase not everyone is buying a phone every month. Marketshare is derived from the amount of people who own your product and it's a percent based on the size of the market, which is a dynamic number (always changing, the smartphone market is growing). RIM's sales are actually pretty decent, especially world-wide - growing even. The problem they have is that their growth in sales is not keeping pace with the growth in the market, currently. Unlike Nokia, RIM still makes money.
WP7 has like 2% marketshare. RIM probably has 10-11%. Microsoft as a whole has like 4% or so if you add in Windows Mobile.
It's literally impossible for RIM to drop to 3% from where they were unless every consumer in the country threw their Blackberries in the trash, and even then they'd probably still end up with more marketshare than WP7 by virtue of Government and Corporate sales.