If for some reason you don’t want to use to jailbreak your iOS 5, here is a good alternative utility – Sn0wBreeze 2.8b8. It can perform a tethered jailbreak for iPhone 3GS, iPhone 4, iPad 1, iPod Touch 3G and iPod Touch 4G.
As usual it will preserve your baseband (modem) version for unlock with or Gevey Sim.
You can download Sn0wBreeze 2.8b8 .
UPDATE: Sn0wBreeze 2.8b8 step-by-step jailbreak and unlock tutorials:
H8sn0w has just released the new version of Sn0wbreeze 1.4. Sn0wbreeze is a jailbreak utility with functionality similar to PwnageTool. The new version supports firmware 3.1.3 jailbreak for the following devices:
Sn0wbreeze is a Windows application, so Mac users have to wait for the upcoming release of PwnageTool by the DevTeam. Alternatively, both Mac and Windows users can use Redsn0w to run jailbreak (no custom firmware though).
You can download the new version of sn0wbreeze .
MuscleNerd continues to argue that we should not use sn0wbreeze. Especially users who have unlocked their iPhone with blacksn0w utility:
In addition to announcing a new version of Redsn0w, MuscleNerd has announced a PwnageTool port to Windows and Linux:
When asked about PwnageTool, MuscleNerd said via twitter “they can compile now for wxwidgets for redsn0w 0.9, so pwnagetool port can be based on this”, “and so that means, pwnagetool port for windows and linux. For OSX it’s all on @wizdaz of course 
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PwnageTool lets you build custom ipsw files which can include personalized boot logos as well as automatic installation of applications. There is also project called Sn0wBreeze, a port of PwnageTool to Windows. However a port from DevTeam is of course more preferrable.
The latest version of PwnageTool 3.14 can be downloaded here.