While still early on and a bit complex, downgrading the HTC EVO 3D from HBOOT 1.50 to 1.40 on Sprint/CDMA was accomplished yesterday, meaning you can get your phone into a state that allows you to run Revolutionary's S-OFF unlocker.
The process is complex, requires booting a computer into a functioning Linux OS at the moment, and works best with two SD cards. At the least, it requires a computer with the ability to write to the EVO's microSD card, a wall charger, and liquid courage. It's not for the faint of heart, and it's guaranteed to, at least temporarily, brick your phone for the exploit to succeed.
With S-OFF you'll be able to update or change the radios without reverting to stock and having the phone wiped twice, as well as lock and unlock the bootloader at will, all without raising flags that you are unlocked or re-locked. Oh yeah, for people who pledged on the S-OFF bounty, you might want to get ready to pay someone.
Personally, I would suggest most of us sit back, wait a few days for someone to develop an automated process that does not require jumping through the hoops this does, but should you be interested in trying it now, check the link below as evidently it works.