No guarantee that it works as advertised yet... ;)
<META NAME="GOOGLEBOT" CONTENT="NOARCHIVE">
<META NAME="ROBOTS" CONTENT="NOARCHIVE">
should work for webmasterworld [webmasterworld.com]
In certain instances you do not want your page to be cached. for example your terms and conditions. These pages may change from time to time, so you only really want the users to have acess to the recent (up to date) version.