Editing options include things like cropping, exposure, saturation, tint, contrast/brightness, soft focus and some simple colour effects.
The app works quite well as you just slide your finger on the screen to adjust the image with the effect you're applying, so cropping is easy to do.
For a free app it's handy to have if you take a lot of photos with your phone as you can edit them up on the move before uploading them. Only thing I wish you could do on it is add text to images through the app as well.
The app can be found on the Market by just searching for Photoshop.
Also if any of you have any apps to recommend yourself, then feel free to name them in the comments and I'll check them out for myself.