Apparently, T-Mobile has began rolling out the Cupcake update OTA, just not in the US. We spoke with a T-Mobile rep that said the update is not currently being pushed to US customers

The Android 1.5 update will include some cool new features such as an onscreen keyboard, a video recording app, the ability to upload videos directly to YouTube and much, much more.

We will be looking out for the 1.5 update and report back as soon as its official for the United States Tmo Customers.