Should I Upgrade My iPhone 3GS to iOS 5.0.1 or iOS 5.1?

Hello Merk, basically both iOS 5.0.1 and the upcoming iOS 5.1 are just to address the battery drainage issue which is mainly experienced by iPhone 4S users. So there’s no need for you to upgrade your iOS device to the latest iPhone firmware. Additionally, the iPhone Dev-Team already confirmed that you might lose your opportunity to get an untethered jailbreak if you update to the latest firmware as it might patch the exploit that is being developed to get untethered jailbreak on iOS 5.

However, if you have an iPhone 3GS with old bootrom, then you don’t have to worry about losing the ability to get untethered iOS 5 jailbreak as you can get untethered jailbreak even on iOS 5.0.1 and probably on iOS 5.1 as well. If you aren’t sure if you are rocking an old or new bootrom, then you can download iDetector version 1.0.1 to help you determine the bootrom of your device. You can download iDetector from iH8sn0w official website. Then once downloaded, just simply connect your iPhone to your computer, put it in DFU mode, and then launch the application. If you get positive result (old bootrom), then you can update your iPhone to any firmware you like as long as it is supported by either Sn0wbreeze or Redsn0w jailbreak tool. Anyway, you can check this blog post on how to jailbreak iOS 5.0.1 using Redsn0w 0.9.9b8.