I thought it had something to do with the scene loading time, but I started a new project, built it and there is still a black screen after the splash, it's not bothering so much when you leave the original unity splash screen or use your own black splash screen, but in my project the splash screen is white, and the loading/logo scene following it is also with a white background, so it's kind of annoying to have white-black-white sequence, looks very buggy and unprofessional.
I think it has something to do with the loading indicator, when I change it to on, I get a black screen with the indicator, when it's off, just a black screen is showing.
I saw an early fix for unity 3.5, but the AppController.mm file does not exist in unity 4.5, I think they changed it to SplashScreen.mm, and I don't know how to modify so if anyone who familiar with those scripts can help me I'll appreciate it.
I used ipod 4 with ios 5.1.1 for testing.