You might have noticed that after upgrading your iPhone to firmware 3.1, all (apps that you have installed manually outside from App Store) Jailbroken apps have stopped working even if your re-install them. So how to run these Jailbroken apps? Jailbroken apps will not work on iPhone OS firmware 3.1 until you patch MobileInstallation file on your iPhone. Here is a step by step guide through which you can unlock Jailbroken apps. You can jailbreak iPhone firmware 3.1 from here and unlock it from here before you may proceed to the procedure below.

How To Apply Cydia MobileInstallation Patch

1. Go to "Cydia"
2. Click on "Manage" tab on the bottom
3. Click on "Sources" as shown in the screenshot below:



4. Click on "Edit" and then on "Add". You will be prompted to enter a url source as shown in the screenshot below. Type "http://cydia.hackulo.us" and click on "Add Source"



5. Cydia will now automatically update your sources by following a series of automated steps





6. After installation is completed. Search for "AppSync for OS 3.1" in Cydia and install this application. This app will automatically patch your mobileinstallation file

Yeah! Now you can easily install / run Jailbroken iPhone apps on iPhone OS firmware 3.1. Enjoy