In France, one often notices that silverware has been placed with tines touching the table, which can look funny if you've never seen it before. The only time this looks absolutely correct is when using the family silver, to show the crest engraved on the back. In this case, you may actually reverse the silverware so that the fork tines and knifepoints are facing you instead of the diner opposite, which on reflection, seems alot friendlier than pointing the knife end towards the diner sitting opposite you.
Apparently, at one time, it depended on the surface of your table. If you were setting a valuable teak or mahogany table, and there was risk of scratching, than the tines were not to touch the table. With the addition of tablecloths, silverware could be placed tines down.
