The iPhone Dev Team released a new version of RedSn0w late last week that includes several major new features. At the top of the list is the inclusion of Cydia in the tethered jailbreak for A4-equipped iOS devices. Previously iPhone 4/3GS owners had to use SSH to install Cydia manually. This latest 0.9.15b1 version also lets owners downgrade to earlier firmwares without jumping through a bunch hoops that require you to stitch your SHSH blobs together with your IPSW and ignore multiple iTunes errors during the restore. You can read the full changelog and detailed install instructions on the iPhone Dev Team's blog.