As of roughly one hour ago, the Chronic-Dev team have released greenpois0n with support for OS X, Windows and Linux. A few days late, but revised to ensure integral system exploits aren’t unnecessarily exposed to Apple, users of all popular platforms can now free their iOS devices.
Greenpois0n is an alternative to Limera1n, that uses the same exploit delivery and payload as geohot’s tool but built by the Chronic Dev Team. It allows users to jailbreak the iPhone 4 and 3GS as well as variants of the iPad and iPod Touch devices running 4.1. Not much separates these 2 applications from a users point of view, however greenpois0n is said to be more stable and have better support, coming from a team who have been on the iPhone scene since the beginning.
If you run into any issues, the team is available in #greenpois0n on irc.chronic-dev.org for questions and limited support.