In the past I've had to go into the SQL db and use this option to cancel out some hung tasks. Never noticed any "bad" side effects from it.
I wouldn't allow your users to do this though, this should only be for an Admin, preferable someone with some SQL experience/knowledge.
Thanks for the reply Tom!
Our plan wasn't to allow everyone to start meddling around in the database. We currently have a web page that queries the database and displays a table of the in-progress tasks. This allows users that aren't privileged to see the Admin Tool to still monitor the progress of their long-running tasks (which are initiated through CAD). The plan was to add a Cancel button to the table that would allow users to cancel only their tasks. This cancel button would call a stored procedure to set their task status to cancelling/canceled.
We've done the same for hung tasks in the past. We're hoping to see if it'll work for tasks that are in-progress but not hung as well.