Howdy Google Siters,
Google have added a feature which allows you to hide 'Sign In, Recent Changes or the Print Page etc' links from the automated Google Sites System Footer.
Just log into your site > More Actions > Manage > Site Layout > Customise System Footer Links > decide which links to hide (unfortunately you can not remove them all just the ones I mentioned earlier but it's a start!) > click ok > click save changes
Let me know if you have any problems.