Its available at SPD: http://www.smartphonedepot.com/produ...00_themes.html
However, it does not work properly on OS 3.8. It does not load up the fonts correct, however, it does load the background up (although its not available as a background image in picture viewer). You get black fonts not white with dark blue border (and vice versa for highlighted text) - not very attractive.
Wait a week or two for TMO and Cingular (and Rogers) to release the 7100 OS4.0 and then grab the theme file from SPD and load on there.