On a mainstream site like wired its almost always flash ads. It can also be jpegs (see http://www.checkpoint.com/defense/advisories/public/2004/cpai-2004-42.ht

On a mainstream site like wired its almost always flash ads. It can also be jpegs (see http://www.checkpoint.com/defense/advisories/public/2004/cpai-2004-42.html http://www.checkpoint.com/defense/advisories/public/2004/cpa...) but this is rare/patched.