If you unlocked your Windows Phone 7 thinking "no one will ever know", think again. Microsoft has sent an Over-The-Air revoke for ChevronWP7's certificates, thereby relocking all Windows Phone 7 devices that had previously been unlocked. To the end user, this means any homebrew applications you might have installed will no longer run, but for the time being, you can always re-unlock your device.
Microsoft hasn't released any official statements as far as we know, though there is a chance that the certificates were pulled as a maintenance procedure (or something of the like), as Microsoft would probably take credit for any homebrew take down if they really wanted it gone. What do you think?
Update: As we suspected, Microsoft is not specifically targeting the unlocked devices. Rather, the operating system is set up to, once unlocked, phone home on a periodic interval (roughly 2 weeks). As the ChevronWP7 team writes:
Contrary to circulating reports, Windows Phone 7 devices unlocked via ChevronWP7 are not being targeted by Microsoft. Instead, the phone is reverting back as a result of a periodic check. Simply put, the phone rings Microsoft and asks “Hey, am I supposed to be unlocked?”. If Microsoft responds with a “No, what are you thinking?”, the phone apologizes and initiates a lock down.
A bit of a relief, but certainly a plateau in Windows Phone 7 homebrew efforts.