For those going with HTC as their WP7 choice, you'll be of course getting their allotment of special software, including Weather, Stocks and the focus here, Photo Enhancer.
The app itself looks really nice in this video hands on by 1800PocketPC, with a wide-assortment of filters to choose form, smooth UI and just an overall great experience. While not a complete photo-editing package e.g. cropping, sharpening, etc. don't seem to be there, it looks like a great addon.
And for those not going with HTC, you can always check out Picture Lab which looks even more impressive. See the full video hands on after the break!