Access to the OS clipboard would require the use of Flash. I would like to stay away from that. We'll see what our options are. Thanks for the feedback!
Access to the clipboard are reasons why I still install apps like Grabbox, Tinygrab, etc (less steps I have to take). Hesitance over the use of Flash for a usability gain for the user seems like a silly sort of squeamishness (look at bit.ly's copy to clipboard buttons).
I suggest you add Cntrl+V uploading of images from the clipboard; it's a great feature which a lot of sites have overlooked.