Adobe Eazel for Photoshop is an iPad app that enables you to use your iPad like a digital canvas. You can work with digital paint using your fingers on your iPad's touchscreen, blending together wet and dry paints to create the look you are trying to achieve.
The app is fairly well thought out, and by default all paint controls are completely hidden from view to help maximise the area you have to work in. A five finger gesture is all that is needed to bring the controls into view, and you can then adjust paint and brush settings as required.
Once you have completed your work, your creation can be transmitted to Photoshop CS5 - and this is the only version of Photoshop that is supported - assuming your iPad is on the same network as your computer. You also have the option of sharing files via email, but the higher resolution that can be achieved using Photoshop transfers is not available using this method.
Despite the price tag attached to the app, Adobe Eazel currently feels like something of a novelty rather than a completed product. Hopefully over time improvements will be made to justify the cost, but as things stand this is a somewhat disappointing app from such a big name, especially considering Adobe's other ventures in iOS software.