The long awaited jailbreak for A5 chip based devices including the iPhone 4S and iPad 2 has now gone live at Greenpois0n. This is an OS X version, but a Windows version has been promised as coming soon. The long wait for this jailbreak has resulted in great anticipation and their website is getting pounded right now. You can certainly try to download it, but expect long wait times.
As always, if you need help, hit up the Jailbreak forums here on everythingiCafe.