The ability to upload attachments from the command-line would be nice.  Ideally both indicating a filename to upload or piping (preferred!) to the command (a la fpaste) would be cool.

At a minimum, I would like to be able to specify a description and pass a file-name or read from STDIN.

The options for attachments (type, description, comments, obsoletes, privacy, etc) might be complex enough to warrant a new major command rather then adding things to modify, but I have no preference.