Hadn't seen the link posted on here yet. Just in case...
Save to the root of your sdcard as "update.zip" and flash with recovery.
No, this is not rooted. No, this won't flash over the leaked 2.3.3 PC10IMG from May (you guys can update in-store.) No, this will not flash with CWM so you need a stock G2 recovery to update. Yes, you will lose S-OFF.
After visiting and calling several T-Mobile stores today, none of them had the sdcard update. I decided to use the zip file from Kevin and it didn't work at first. I got stuck at a black screen with a phone and a red triangle picture. I did some digging on a forum at xda developers and found the solution to my problem. Here's what I found on xda and it worked.
"Rename file to update.zip (make sure it's not update.zip.zip)
Put it in root of SDCARD
Power off phone
Press volume up and power to turn on. Choose the second option (RECOVERY)
Once You get to the red triangle with exclamation mark press and hold VOLUME UP AND POWER
Now You'll see a menu,
Choose "apply update.zip" and wait.
Then You'll have to reboot.
After the reebot You'll see a phone with two green arrows, just wait
Then the phone will reboot and You'll have Gingerbread"
Took about 10 minutes total time, update was pretty painless and I still have all my data. NO FACTORY RESET!!! I was totally stock G2 2.2, no root.
Was anyone using the leaked version of 2.3.3 that had backlight issues and the 2.3.4 release fixed it? Just debating on whether I want to force the update or wait for the OTA to spare losing all apps and such which wouldn't kill me. Posting this, by the way, using RemoteDroid which is pretty freaking neat.