Verizon is a CDMA network and AT&T, T-Moblie and the others folks use iPhones on are GSM based so you can't cross network types. I did hear the iPhone 5 will have both CDMA and GSM radios in it so they can only build one phone for both Verizon and AT&T.
My iPhone is jailbroken too and there is much more you can do with it than just unlock it to use on other networks. The are themes you can install so the ability to customize the look to your preferences is almost infinite. There are also lots of Apps Apple won't allow on the App Store that do some truly useful things. I have a calendar, weather and appointments on my lock screen. I can also compose text messages and make calls from the lock screen or without disrupting any of my other running apps.
