I did some research about how much use each mobile platform gets for browsing the web.
I looked at two different reports, which both basically said the same thing.
In North America, when people use the mobile web they are pretty much on iPhone, Android or Blackberry.
The rest: < 5% each
Just wanted to think about twitter for a minute. Twitter gets huge percentage of its hits from mobile and processing almost a billion SMS messages a month.
They've also said that their blackberry app gets 8% of their new sign-ups:
And a WAP vs Mobile Web discussion: