Unless I'm missing some detail of what you're saying, HipChat already does that. I regularly drag screenshots into a conversation. Hipchat uploads them to S3.

Unless I'm missing some detail of what you're saying, HipChat already does that. I regularly drag screenshots into a conversation. Hipchat uploads them to S3. There is a size restriction, though, which I've run up against more times than I can count, since I never seem to be able to remember that it's there.