Orientation Lock requires the task switcher, so I understand not including that. Missing wallpapers probably works but slows down the OS due to the lack of ram, heck my iPhone is already hard to use because of slowdown, (The only explanation I can come up with is that I just have too many apps or something, (though it shouldn't be how many books on my bookshelf, but how many books I have open, and on the 3G only one book... or app in this allegory, can be open at once so I am not really sure why that slows it down). So I think they should include the options, especially for wallpaper, but I understand why.
I also haven't been able to get wireless bluetooth keyboards to work on the 3G on iOS 4, I am not sure if thats just me, or if that has something to do with the iPhone 3G only being bluetooth 2.0 rather than 2.1. If anyone could confirm that as being a 3Gs/4 exclusive that would be helpful.