Sure, we'll probably know way more in another few hours, but lets tease a bit more, shall we?
Evidently, if you search on Sprint.com for "Arrive" you get this little result above, confirming what everyone already suspected: the HTC 7 Pro is going to be the Sprint HTC Arrive. We also like the emphasis on the wording here: "the first Windows Phone from Sprint", strongly hinting that the carrier is just getting started.
We also know that we'll have to pre-order the phone, meaning tomorrow is not the release but the announcement (also pretty normal for Sprint). Anyone want to take a guess on shipping? And lets hope we don't actually have to go to a Sprint store to pre-order....
Thanks, Matthew, for the tip!