A new feature known as "parameter handling" has been recently introduced by Google under site configuration of Google Webmaster Tools.
Google Parameter handling is meant to inform Google as to which parameters in the URL they should ignore. It is highly useful technique for tracking the parameters added to the URL. Duplicate content caused by printer friendly URLs and so many other related problems, can be easily traced out by Parameter handling.
Yahoo Site Explorer supports the above feature referred as Dynamic URLs by Yahoo! For more visit Yahoo Help.
Google help document provides more information on this new feature.
