An applescript can return its result to the first pane via qs command line tool if 'Run tasks and actions in the background' is enabled, in the form
do shell script "qs " & myResult
If that same applescript is configured as a trigger Quicksilver only logs "Task succeeded", but it doesn't show the result in the first pane.
See this topic https://groups.google.com/forum/?hl=en&fromgroups=#!topic/blacktree-quicksilver/e7AlkhVIdEo