I just happen to slap my SIM card into my 9900 again last night and "Check for Updates" and it's here! OS 7.1 has Wifi Calling and Wifi sharing. I was really looking forward to the wifi calling, since I use it in Antarctica. I actually bought this phone before I left for the ice, and haven't used it at all since it lacked UMA. I was unhappy, since Blackberry's have traditionally always came with it, I just expected it. Anyway, battery life kinda sucked too.
I did not think Wifi Sharing would be a big deal. I've always been able to use bluetooth or USB. I recently updated my iPod touch to iOS 5.1 and haven't jailbroken it. I was only jailbreaking it to use Bluetooth dial-up to the blackberry..
Now I can be legit on my iPod, but sorta break a silly rule on the Blackberry. You're suppose to pay $15/m more to use this feature. A software feature of the phone. They already limit our data per month. I've been a T-Mobile customer forever, and it use to be OK to use your BlackBerry data plan for USB/Bluetooth tether (It was already $15/m more than the "feature phone internet").
There may be another way, but I was able to get the 'Mobile Hotspot' service to prompt me for the APN to use by using BBSAK (BlackBerry Swiss Army Knife) and overwriting net_rim_cldc_impl_mhs.cod from an earlier leaked version, 184.108.40.206.