iH8sn0w has released his latest version of Sn0wbreeze for iPhone 4, iPhone 3GS, iPod Touch 3G & 4G, as well as iPad. The benenfit of Sn0wbreeze over Redsn0w is that Sn0wbreeze allows you to create custom firmwares as well as preserving your baseband. You will also of course need iTunes 10.5 Beta 3 to restore your new firmware.
As a reminder, iOS 5 Beta 3 is for developers only. Your phone’s UUID must be registered with Apple to bypass Activation. The reports of the App Store App’s crashing was fixed in the latest version of Redsn0w. You can find that download here. the App Store issue is however not being reported with Sn0wBreeze, so feel free to use either the newest Redsn0w or the this version of Sn0wBreeze.