I've been having trouble trying to create a full screen modal view on an iPhone application, but when I present it if it is in landscape, the view will be in one small portion of the screen. If it appears, and then you rotate it to a different orientation, it will either be a white screen, or a shrunken window in a corner. Here's how I call it:
bookmarks.modalPresentationStyle = UIModalPresentationFormSheet;
bookmarks.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentModalViewController:bookmarks animated:YES];
bookmarks.view.superview.bounds = CGRectMake(0, 0, 320,460);