yea i have the same problem, it bugged me for a while. I hate the idea of using cabs as a wallpaper because i tire of them quick. I know this may be a drawn out and ridiculous solution but i have an app on my ipod touch that has a bunch of wallpapers. After them being stretched out on my TP i decided to try on my TP2... viola!!! it looks perfect...so if you happen to have an ipod with that app you could try
Here is a example:
of course as u might have figured it doesn't really help in landscape mode