A few months back Research in Motion announced a new BlackBerry Application Suite that essentially is BlackBerry OS Virtualization Software that will run on select Windows Mobile 6 powered devices that emulates the BlackBerry OS and allows it to run as an application within Windows Mobile.
BGR believes that the Virtual BlackBerry client will make its debut on the T-Mobile Dash. This little tidbit is clearly still in the rumor phase, however, Boy Genius has been right about this kind of stuff many times before.