The one thing I'd love to have in iOS 5 is the Apple TV software / Frontrow available on the iPad: Being able to use the iPad as an Apple TV with a built-in screen would be a real killer feature IMO. And before people start suggesting Air Video or similar from the App Store, they don't support DRM protected files and as 80% of my videos are from the iTunes store, are useless for me
I don't think they'll do the Apple TV interface. However, I do think home sharing will be coming with iOS 5 and that will fix your problem (your iTunes "shares" will show up within the iPod.app and Video.app allowing you to stream content from PC/Mac to your iOS device.).