Today I has a 3GS that i updated to 6.1 and was unactivated after restore. So what i did was this:
1. Download latest redsn0w
2. download a copy of iOS6.0 for your iDevice. You can get one at the website iclarified.com or felixbruns.
3. When in redsn0w go to extras and click Select IPSW. select the ios 6.0 you downloaded. hit back and jailbreak.
4. done
This works with 3GS or iP4. With later devices just use evasi0n and jailbreak.