From Cnet to all the gadget sites, there is a buzz that tomorrow, May 4th, tmo will be offering this upgrade on their site.
Take a look at these two site:
They can provide more info.
I also believe one of them has a report on the Dash that has already been updated. **edit** Engadget has the story. they just have the pics of the new OS on the dash.
Is this true, i cannot wait. I also hear that it will be absolutly free on T-mobile.com