All right, I'll be the nice guy who doesn't tell the new dude to search...
First of all, I'm going to assume that by Unlocking you meant Modding. Quick vocab rundown:
Unlocking: Unlocking is hacking the phone so that it can operate on another carrier than the one you're strapped with.
Modding: Installing additional applications on your phone.
As for safe, there has been and always will be some sort of danger in unlocking and/or modding. Because anything you do with them isn't necessarily made to work with the iPhone, there's always a slight chance that you will brick your phone, or as Apple puts it, make it permanently inoperable.
However, in most cases, if anything goes wrong, you can Restore in iTunes. Restoring will return the iPhone to it's original settings and software, and will delete anything you have Installed.
Note: While modding can be completely undone with Restoring, unlocked phones can not be restored. To re-lock them, you will have to use a program called Revirginizer.
If you're using Firmware 1.1.1, navigate here to jailbreak (modding, NOT unlocking) your phone.
is it true that if you buy an iPhone, register it, acquired 2year contract from AT&T
you can go to them and ask them to unlock the iPhone for you legaly?
i know it sounds dumb and stupid but everything is since you have a quad
band cell that you cant use somewhere else like different country just because
AT&T said so.