Cloaked URL's allowed by PPC?

Do adwords and Yahoo allow cloaked url's for their PPC campaigns? and can they be used for tracking purposes?? if so how??

If you are thinking tiny or snip url, they won't work because google wants the display and destination url to be the same (going to the same site, destination url google.com/adwords, display url google.com). Destination url from tiny or snip url will go first to their servers and then to the site you are promoting.