Sure you can – and you can make it yourself!!
Over on The How To Geek there is a post about the guy that brought us Vista Thumbmail Resizer who is now working on a way to create your own Vista Theme. From the looks of the shots, there will be the ability to add your own images, resize certain elements and many other changes. It’s not going to be free, but it sure might change some things for the Touch users out there trying to peck everything with their fingernail (Been there?? I sure have). Check out Vista Style Builder and keep an eye on the site for availability.