After some people upgrade to 1.3.0, they are running into problems build their projects. What can you try to get your application running?
Here are a few things to try:
Building for the device
If you're running older versions of the iPhone SDK on OS 10.5 (lower than version 3.2 final), you may run into problems deploying to a device (an "Install Failed" error dialogue). We should have a fix for this shortly, but for now you can manually install the binary from a terminal window (which should still have been built correctly):
open -b com.apple.itunes [project_dir]/build/iphone/build/Release-iphoneos/[yourapp_name].app
I upgraded my SDK version, but my app won't build!
It could be that there are artifacts in your build directory that are conflicting with the build scripts used by Titanium Developer. A quick fix to try is to create a new 1.3.0 project, copy over your application's resources to the new app's resources directory, and then run the new 1.3.0 app.
I can't import/run Kitchen Sink!
Try the above with the Kitchen Sink files.