Tonight, Apple pushed the availability of iTunes 10. iTunes 10 has some issues with our detection script in Titanium and we have posted a patch here. To apply the patch:
1. copy the file into the following directory: /Library/Application Support/Titanium/mobilesdk/osx/1.4.0/iphone and name it prereq.py. (In some cases, Titanium is installed in your personal directory under ~/Library/Application Support/Titanium/mobilesdk/osx/1.4.0/iphone/).
2. in the console, make sure the file is executable: chmod a+x prereq.py
Now, Titanium will correctly detect the appropriate iTunes version and you should be good to go. This fix is already applied to master in Github.