The catch -- there usually is one -- is that the application is currently only available to Americans and Canadians. Which means us Europeans are bang out of luck. If you've got a rebellious streak in you, you could probably hunt it down through other methods and install it manually, but we'd never condone that.
The Android Photoshop application gives you a very generous set of features. To start with, it trawls through your phone finding any images you've got stored on the SD card. In our test, it managed to locate every single photo from our Twitter client, which meant there were lots of low-quality avatars clogging up the gallery. Scrolling through everything is easy enough though, and the app is fast, responsive and has yet to crash once.
Once you find an image you want to work with, doing so is a simple matter of selecting it on the home screen and pressing the 'edit' button. From there, you can tweak the crop, adjust light levels, colour and contrast and do the usual tricks of converting photos to black and white. You can even add sepia tones to your images -- you know, in case you miss the days when cameras rendered everything in shades of brown.
Because the Photoshop app comes under the photoshop.com banner, you also get the opportunity to upload your pictures directly from the phone interface. You'll need to have a photoshop.com account for that to work -- accounts are free, or paid, depending on how many photos you want to store, but everyone gets 2GB included, which should be more than enough for mucking around with a few camera-phone snaps.
A good effort from Adobe. It's just a shame that it doesn't seem to care about the world outside the US and Canada.