Why not just use picasaweb?
The real beauty of Hello was that you could drop an image onto the chat window and it was there, almost instantly, a nice big preview of the image on the left of the chat pane, and you could discuss the finer points about the image in real time. During conversation, you'd be like, oh heck, I almost forgot about this one too, check this out...
and you'd drop another picture and immediately begin talking about it. As you dropped more pictures during the conversation, a nice little filmstrip of thumbs would build up along the bottom allowing you to flick back and forth amongst the pictures shared during the session, and if you began talking about a different picture, a little P.I.P. allowed you to see what picture your chat partner was currently looking at, and vice-versa.
While all that was going on, the original, full sized files, with all metadata would be transferred between the two parties in the background, saved to a specified location, thus allowing the auto-import feature of your chosen image handler to automatically detect these new images and import them, tags and all.
Simplicity itself.
picasaweb, if I understand correctly, involves signing up, then uploading anything you want to chat about, then, after waiting for the uploads to complete, sending the links to the person you're chatting with, have them load up their browser and view the pictures, then flit between the two applications to chat/view about the pictures. If your chat partner wants copies, they need to do the old, right click, save picture as... on each file they want, and that's only after browsing to the full size copy of each desired image.
Seems like a no-brainer to me. Sadly, I think that google would rather that we used picasaweb too, and uploaded all our images to their servers rather than quick and simple P2P transfers
-marko.