But if there is only one author of WordPress blog, Post Revisions will taking too much space as every revision is a new row in wp_post table. It creates a alot of useless database-entries.
To disable Post Revisions, Add:
into wp-config.php, the wordpress 2.6 Post Revisions now disabled.
In my little opinion, there should be an option in general or writing settings to enable/disable the post revision feature.