<p>What do I gain by adding a timestamp column called recordversion to a table in ms-sql?</p>

Nothing that I'm aware of, or that Google seems to find quickly.
You con't get anything inherent by using that name for a column.  Sure, you can create a column and do the record versioning as described in the next response, but there's nothing special about the column name.  You could call the column anything you want and do versioning, and you could call any column RecordVersion and nothing special would happen.