XDA Members appelflap and impaler747 have put together a battery icon mod for release. The application's purpose is to create a single application that can easily handle battery icon changes for as many devices as possible.
The app is very easy to use, and the end-user does not need extensive hacking and modding experience to utilize it.
The app currently supports the Epic and Samsung Galaxy S with more device support on the way. It is ROM specific, meaning that you will have to make sure the mod you're applying is from your current ROM. The two developers are working hard at not only making this easier, but also more universal with new devices being added as they become available.