The HTC One M8 running Windows Phone is real, and you need only follow a Verizon URL to prove it. HTC hasn't yet announced the rumored device, but a photo sitting right on Verizon's servers seems to confirm that the phone is indeed coming — and likely soon. WP Central's original report says the "One (M8) for Windows" will be available from Verizon on August 21st. Hardware-wise, it's probably the same M8 that's been running Android for a few months now, but this one's clearly aimed at fans of Microsoft's OS.
When reached by The Verge, HTC declined to comment on the photo's authenticity. The company is hosting a press event on August 19th, and it's likely we'll hear confirmation of the new, aluminum-clad Windows Phone on that date. The One (M8) with Windows would mark HTC's first major Windows Phone for Verizon Wireless since 2012's 8X; that phone is still sold for $49.99 on a two-year contract.