I'm surprised you've only just got this now.
I had it about 5days ago. I'm sure I saw a post on this earlier, nevermind
I had my phone plugged into iTunes, I got a pop-up stating a new carrier update.
I clicked update and literally seconds later, it was done. I am jailbroken on 3.0
I've not had any problems with anything, except the interference (which was prior to the update anyway) over the past few weeks.