I just read this was possible. (It never occurred to me to try.)
Just connect up your iPhone (or possibly any other phone) as illustrated to the USB iPad Camera Connection Kit (sold separately) and voilà!, you can import.
This old-school wired method is faster than using Dropbox. However I still prefer Dropbox–I find it more convenient. I just tether my iPad to my iPhone, launch Dropbox on both, and transfer my pics/vids. Sure it takes a bit longer, but not much longer than finding my CCK and USB cable; and there is the added bonus that my data is backuped to Dropbox. But if I am offline, have crap 3G, or expensive 3G, and I must edit that photo or video now, well then wired is the better solution.