Well looky here - the Sprint Diamond has been caught in the “wild” by ksemt7781 of PPCGeeks. We know it's legit because it comes from Mr. Blurrycam (alright, technically it comes from a Mogul, a distant cousin to Mr. Blurrycam). It looks pretty much identical to the original Touch Diamond we showed you in video and images -- we say “pretty much” because the Sprint Diamond looks to have a bit more of a curve at the top and the bottom and a slightly different skin to TouchFLO 3D -- looks like Sprint's tradition of putting their junk into HTC's custom interface (and HTC's tradition of letting them) has a good chance of continuing.
We put the “wild” in scare quotes because technically it's in testing at Sprint now, we can't wait until it's in testing at WMExperts HQ.
Thanks to Jon for the tip!