Found this . . .
Customize and Firmware 2.0
As we all know, the much anticipated 3G iPhone is coming out on Friday, along with Firmware 2.0 and AppStore. There is good news and bad news.
I have attempted to contact Apple, however, they will not allow Customize to be distributed through the AppStore.
Customize 2.0 will still be available through Installer and Cydia package managers, and will run on firmware 2.0 (I am working on making it compatible now).
More Good News
It will still be possible to jailbreak your phone after an upgrade to firmware 2.0. You will be able to use apps from both the AppStore and from Installer/Cydia. This should also apply to 3G Phones. As I find out more, I will post instructions on how to do this.