I was going completely crazy with this problem until I found this thread through Google!
I'm now on my 2nd 8130 from US Cellular (returned the 1st due to this very issue) and I still had the same issues with satellites taking forever to connect, dropping out randomly, or not connecting in the first place.
Per this thread, I installed TeleNav (using the Alltel download link) and everything now works great. Takes maybe 15-30 seconds to establish satellite lock, and once it locks it never loses the signal.
I'm still in the TeleNav trial period, so I can't say whether or not BB maps will continue to work as it does now once the software is disabled.
I'm speculating here, but it seems to me that US Cellular has crippled the BB maps' GPS functionality in order to generate more interest in 3rd party for-pay apps and the eventual return of My Navigator. This theory is strengthened by the reports of GPS suddenly not working well as of this past January. Very disappointing, Verizon-style fascist behavior.
Either way, I cannot get a straight answer out of USCC, and they continue to market their BB's as having "free" GPS. This is false advertising IMHO..
Just wanted to let others know what they are getting themselves into with a BB through USCC.