The AT&T announcement was made later the same day as the Verizon launch, but T-Mobile just shared their upcoming availability. We do not know how long the M8 for Windows will be a Verizon exclusive, but T-Mobile does state it will be available online in time for the holidays. Labor Day is a holiday, right? By the sound of this, it looks like Verizon may have something like a 90-day exclusive.
It is great to see that the HTC One M8 for Windows is the exact same hardware as the and looks to also be consistent across US carriers, with the exception of the wireless radios.
ZDNet One M8 for Windows coverage