Many sites these days let you drag&drop or paste an image into an input field. This would make greenhopper/jira much, much easier to use. my desktop is littered with temp images I've saved just so I can upload them via the filepicker.

For example, github now does this. there are many 3rd party plugins to facilitate, it should be very trivial to implement.
https://github.com/blog/1347-issue-attachments