I am sure Yahoo will be having some sort of internal page ranking system but Yahoo doesn't advertise like Google
great answere. This usually answers most of the questions anyone has. We all keep forgeting this from time to time. cheers.
Where do you think Y! and G get most of their data info from? The toolbars on millions of computers. It's amazing when you think about all of the data they've collected, stored and used to determine and/or tweak their algo's with.