There is a cache. Facebook uses the Open Graph tags, which are available in JFBConnect. You can learn more about them below:
www.sourcecoast.com/jfbconnect/features/...pen-graph-for-joomla
Facebook caches this information on their site and will reload it every 24-72 hours. You can use the Linter tools to both force an update as well as see what Facebook 'sees' on your page:
developers.facebook.com/tools/lint
Hope that helps get you going, but if you have more questions, just let us know!