Installer.app developers have released info on Installer 4, which will work with jailbroken iPhones running firmware 2.0.
“Hi folks! Many of you are wondering what’s up with Installer 4. No, we haven’t slowed down the work on it, and are currently in the final stages of hooking the GUI to the back-end. We will be contacting the authors of the major repositories in a few days to invite them into the testing process and to prepare for the upcoming repository changes.”
If you don’t know about this app, it is software which makes it easier to run non-App Store third-party native applications on your iPhone, using a Mac and a GUI.