Recently an updated version of the the Greenpois0n tool became available for Mac users and allowed for untethered jailbreaking of iOS 4.2.1 devices. Now Windows users are finally able to get in on the fun as well.
As Engadget points out, the official Greenpois0n website is not able to keep up with the volume of happy Windows users at the moment, so here’s a download mirror link that’s a bit more likely to work right now. [Greenpois0n via MagGadget via Engadget]