iOS hacker known as iH8Sn0w today released sn0wbreeze 2.9.2 to jailbreak Apple’s new iOS 5.1. Sn0wbreeze v2.9.2 allows you to create a custom IPSW so you can jailbreak your iPhone, iPad, or iPod touch. Currently since there’s no jailbreak for iOS 5.1 the jailbreak you will get from sn0wbreeze v2.9.2 will be a tethered jailbreak, except for those using an iPhone 3GS with old bootrom which get untethered jailbreak. The tethered jailbreak works on iPhone 4, 3GS, iPod touch 3/4G, and iPad 1.  iH8Sn0w says this update:
- Added Tethered Jailbreak support for 3GS/iPod Touch 3/A4 Users on iOS 5.1 (9B176)
- iPhone 3GS old-bootrom users are untethered on 5.1/9B176 (as usual).
- Bug Fixes (Specifically with the iPad baseband and iPhone 2G).
- Re-added the iPhone Dev-Team’s iPhone 2G permanent unlock ‘BootNeuter’.
Sn0wbreeze 2.9.2 doesn’t jailbreak A5-based iOS devices like the iPhone 4S and iPad 2. iH8Sn0w clearly explained on his blog why sn0wbreeze doesn’t jailbreak the iPhone 4S and iPad 2.
A low level (DFU/iBoot/LLB) exploit is required to start the restoration of custom IPSWs. The past two jailbreaks (JailbreakMe & absinthe) for the A5 worked within iOS itself. These exploits are not capable of bringing the iDevice into a state where it will accept custom IPSWs. Therefore, an A5 device cannot currently downgrade to an iOS revision that Apple is no longer signing (even with SHSH blobs) and it cannot preserve the baseband when updating to a newer iOS revision.
If you care enough for your jailbreak it is not recommended to update your device to iOS 5.1. Updating to iOS 5.1 will cause you to lose your untethered jailbreak and unlock. This is only recommended for those who already accidentally upgraded to iOS 5.1.