[citation][nom]compfreak93[/nom]"-meaning the SIM-free phones can be used with any mobile carrier the user chooses. US-based residents--up until now--were forced to purchase and import the device if they didn't want to be locked down with AT&T." does this mean you can used a cracked iphone with verizon?[/citation]
Any carrier being those that support UMTS/HSDPA/HSUPA (850, 900, 1900, 2100 MHz)or GSM/EDGE (850, 900, 1800, 1900 MHz). Verizon does not, they use CDMA. But you can use T-Mobile and save a lot of money.
TMobile does not work with the iPhone's 3G so just EDGE speeds for internet. But the additional $700 a year for the equivalent basic family package from AT&T just to have 3G with a 2GB cap vs unlimited EDGE just is not worth it.
Now I'm just waiting for them to release the iOS 4 jailbreak and unlock for the 3GS old bootrom. That has never been jailbroken before, already on iOS 4, with no SHSH saved to step back to 3.1.2. I guess I should have read up on the subject more thoroughly before buying a used 3GS.