This is an app that lets you change your reported firmware from 4.0 or 4.0.1 to 4.0.2 - tricks apps like appstore and iTunes so you don't get bothered to upgrade to 4.0.2 in iTunes anymore and so you can install any current appstore app. There are benefits to this:
1) 4.0.2 is just 4.0.1 API with jailbreak closed. 4.0.1 is just 4.0 with the signal bar graphics and algorithm changed. So any app written for 4.0.2 should run on 4.0-4.0.2. There is no point letting appstore prevent your install. Appstore developers that force 4.0.2 are idiots. You can solve this yourself now.
2) This prevents iTunes from nagging you to update your iPhone firmware or auto updating it. If you have a non-technical user using the device, this prevents accidental updates to 4.0.2 wiping out the jailbreak. You must reboot the iPhone after installing this in order to have iTunes recognize the version 4.0.2.
Note: This does not really update you to 4.0.2. Instead it just tricks your device into thinking you are updated by updating the file at /System/Library/CoreServices/ SystemVersion.plist. In general, I think firmware spoofing is a bad idea. But this is a unique time where many users are accidentally updating and losing their jailbreak and where the firmwares are so similar spoofing does not matter. Therefore, this package will help that.
Note: this app also installs Saurik's PDF exploit patch which closes the PDF exploit hole that 4.0.2 is protecting you from. In this sense, it is almost a real 4.0.2 upgrade without losing your jailbreak.
