If you don’t know what firmware you are running on your iPhone, iPod touch or iPad, follow these simple steps to find out which version of iOS your device is on.
The first step is to open up your Settings application. Once here, select General and then About.
You can now see certain specs such as how many photos you have, how many songs, etc. but most importantly your firmware. As you can see I am currently on iOS 5.0 build 9A334. So now that you’ve found your firmware version, click here to find the right jailbreak for you!