There is a new remote unlocking via IMEI available for all GSM iPhones. There have been a few forum goers mention they can do it, which seems a bit shady (no actual business, no way to get money back other than trust, etc).
Here's the gist of it - you pay someone $175 (that seems to be the going rate across everyone we've heard from), and send them your iPhone's IMEI. Within 24 hours, they send you an email saying it's unlocked. You then sync with iTunes, and your iPhone is unlocked. That's it. No codes to enter - you're just unlocked. It doesn't work with Verizon iPhones (they don't take a SIM card), and it doesn't work on any iPads. But any GSM iPhone - $175 for an unlock that won't care what firmware, update, or jailbreak status you're on. Just like a factory unlocked iPhone (which it basically then IS), it's unlocked for the life of the phone.
How does it work? Well - Apple has a database already which they query when you do a sync in iTunes to check your devices lock status. That's how it works if you call your carrier and they unlock the device for you - you sync in iTunes and it is unlocked. There is a source wholesaling remote unlocks, and many in the industry suddenly today picked up the ability to do this. It would seem someone with access to this db is basically selling that access - as far as the research shows, everyone who is selling this is getting it from the same source. This could be totally sanctioned and legit, or this service may just as suddenly stop being available one day (although once you've been unlocked you'll be so forever).
If you've got a need for this, and your carrier isn't going to do it for you - this is good news.
