How to disable Post Revision feature

I just upgraded my blog Internet Directory to wordpress 2.6.5 and I was wondering if there is any simple plugin which will disable the Post Revision feature only.

I want to keep auto save feature.

I searched the forums but couldn’t get a simple pluging to do just that.

I waqs wondering why this feature is not inbuild with WP as it would be one of the desireable feature.