After upgrading to 3.0 iPhone software, you might want to install AppSync to allow yourself to install your cracked apps to work. MobileInstallion is not needed this time.
Open Cydia (DONT USE ICY)
Add this source: http://cydia.hackulo.us
install AppSync or installd
Restart iPhone
Connect iPhone to your PC/Mac by USB-Cable
Copy cracked ipa files into your iTunes Library (just drag and drop to the iTunes Window)
Tell iTunes to install applications that you want
Start Syncing iPhone!
enjoy it!