TinyUmbrella, the tool that allows you to save SHSH blobs of iDevices, is now updated to support iOS 5.0.1 on iPhone 4. TinyUmbrella 5.01.00 includes support for iPhone 4S, in addition to already compatible devices, including iPhone 4, iPhone 3GS, iPad, iPad 2, iPod Touch 4G/3G.
Currently, there is no way you can downgrade iPhone 4S firmware. However, by storing SHSH blobs for your device, you can ensure that you will be able to perform a downgrade when, some day, it becomes possible.
iPhone 4S has been recently jailbroken by the iPhone Dev Team. The jailbreak has been demoed on video, but a public release is not expected any time soon. According to MuscleNerd, Dev Team member, the jailbreak is still in a preliminary stage, and lot of work needs to be done before releasing it to the public.