Installer.app, the app store before that other app store, is coming back for firmware 2.0 and being re-fashioned as Installer 4. Currently, jailbroken 2.0 iPhones are using Cydia as their main app pipeline but when Installer 4 is released, well, they'll likely play nice with one another and especially nice with that other app store.
The RiP Dev Blog has a lot of complicated, programmer's type language describing the updates for Installer 4.0 so I'll try to translate to more understandable, layman's terms: It's going to be faster, safer, and more integrated. Bang.