Leon, if the images are transferred to the ipad via the Apple camera connection kit, or I assume taken with the iPad, they can be deleted on the ipad, independant of itunes. similarly if images have been downloaded, they can also be deleted on the iPad. If you press the arrow at the top right you'll be presented with options which include a selective delete which will work on all images except those transferred in using ITunes.
If you haven't already got one the camera connection kit is a must, simply connect the usb from your DSLR to the ipad and the ipad will invite you to transfer the images, with or without deleting from the camera. The camera adapter also works a treat for sharing images between idevices. Saves stuffing around with iTunes.
http://store.apple.com/au/product/MC...connection-kit