As pointed out by 9to5mac, Adobe has just released its new Adobe Photoshop Touch for iPad app to the iTunes App Store. The new app will allow you to make basic adjustments to your photos.
If you're familiar with the desktop version of Photoshop, you'll notice this is a little more stripped down, but very useful for editing together a great photo. Photoshop Touch includes basic features that will allow you to add filters, make adjustments, and add layers. You can also use your iPad's camera to take pictures and directly import them in.
Adobe Photoshop Touch for iPad features: