In an uncommon outbreak of entente cordiale, iDevice hackers Chronic Dev Team have released a jailbreaking tool based on Geohot's Limera1n exploit.
As we previoulsy reported, notorious Apple-bater Geohot released the current boot rom hack just hours before the Greenpo1son version was due to be outed, but as the two hacks use completely different methods of attack, the current jailbreaking tool uses Geohot's work, which covers the latest hardware as well as some legacy devices.
Which means that the Dev Team have a second working exploit in the form of SHAtter held in reserve for when Apple closes the hole, although Geohot is confident the hole can't be closed using a firmware update.
Greenpo1son is available now but with some caveats. You'll need to follow some pretty detailed instructions if you don't want to lose your carrier unlock and end up with a very expensive paperwight. The Mac version is currently unavailable, and we're hearing a worrying amount of reports that the toolkit fails to install Cydia in some cases.
Best advice is probaly to leave it a few days until the release matures a little, and make sure you do your SHSH backups.