Those looking forward to an untethered jailbreak solution on the iPhone 4S should heed the words of developer pod2g, who warns that the iOS 5.0.1 update should be avoided for now. The reason is because security exploits found in iOS 5 have been closed by Apple in iOS 5.0.1. These security flaws, publicized by security expert Charlie Miller, will simplify the untethered jailbreak process on the iPhone 4S.
If you're concerned about the security flaws, there are no reports of any malicious software actually using these exploits to do harm. Regardless, after the iPhone 4S is fully jailbroken developers will patch iOS 5 on their own with updates available through the Cydia jailbreak app store. The point is that if you plan to jailbreak your iPhone 4S untethered in the near future, the iOS 5.0.1 update should be avoided until further information is available.
For those with older iPhones, if you have already updated to iOS 5.0.1 all is not lost. This latest firmware from Apple can be jailbroken semi-tethered using redsn0w. You can follow these instructions to jailbreak your iPhone 3GS or iPhone 4 using redsn0w with iOS 5.0.1 firmware. Again, these will be tethered jailbreaks unless you follow the steps to semi-tether your iOS device. Lucky owners of the iPhone 3GS with an earlier bootrom can jailbreak iOS 5 or iOS 5.0.1 untethered with the current version of redsn0w.
For those with an iPhone 4S or iPad 2, rest assured that developers are working hard on bringing a jailbreak solution to your device as soon as possible. The key for now, if you're interested in a future untethered jailbreak solution is to avoid iOS 5.0.1 until further notice. For what it's worth, reports have been mixed on whether or not this update helps to improve battery life. For some users the update has actually caused more of a problem in this regard. Hang tight for more information, we will report on the iPhone 4S jailbreak as soon as it's available.