You can take a look at the following KB article - How to reduce the project database size . The script will clear the history for pages and content items. We will consider "clear history" implementation from the UI in one of the SP and Sitefinity 4.0
Make Sitefinity work best for you.
Progress, Telerik, Sitefinity and certain product names used herein are trademarks or registered trademarks of Progress Software Corporation and/or one of its subsidiaries or affiliates in the U.S. and/or other countries.