I just upgraded to iPhone SDK 3.2 Beta 4. Since doing so, I have not been able to get the app to launch in the iPhone simulator - it keeps launching in the iPad simulator. I
I finally solved this problem myself.
First, install new version of xCode, which is xCode 4.
Then set project scheme to iphone simulator and run app in xCode several times.
And re-install xCode 3 and the problem will be gone away!