We have a workflow action on our Case object titled "Take Ownership". The Take Ownership workflow action can act against one or more case records and it immediately sets the Owner field to the current user on affected case records. The workflow action is a direct action in that it does not direct the user to a change status page. Unfortunately, this method does not abide by any kind of record locking restrictions.
In our scenario, a person can be editing a case then another user could use the Take Ownership workflow action to change the Owner value of the field on the case record currently being edited. No record locking error every displays to the second user. The end result is that the person first editing the case will then save the case, thus re-writing over the recently changed Owner field on the case!
Record locking needs to be enforced at all times no matter how a record gets updated (by direct editing in the browser, via workflow actions, via data imports, etc.).
Sorry, title of this idea should be "Need to enforce RECORD locking for workflow actions".