Two different threads at two different forums are complaining about how Yahoo! is indexing and listing in the search results pages, URLs with tracking codes. Let's pull out one specific example, from the Search Engine Watch Forums thread.
The URL listed in the results can be seen in the Yahoo! Search results in the 3rd spot (currently) for Fargo ND Lodging, it looks like:
So why is the www.cmoninn.com/fargo-nd-hotel.htm?source=googleadwords indexed? My first impression was that someone linked to it and Yahoo! picked it up. But at the time of conducting a link lookup I received zero results, so that kind of means Yahoo! says there are no external links to that specific URL. Of course the search index can be more frequent or less frequent than Site Explorer, so that can also explain it. FYI - there is now a link to it from SEW forums but that was after the fact. Plus this won't help the person in this situation remove this URL from the Yahoo! Index.
So what is going on? Yahoo! said there are no links to it. How did Yahoo! pick it up?
Well, just looking at some Yahoo! results you can see quit a few have dynamic URLs that appear to be tracking URLS. The 2nd result for that search above shows, local.com/results.aspx?keyword=lodging&location=Fargo, ND. The 4th result shows, orbitz.com/App/ViewSpecificHotelLP?masterId=65069. The 12th result shows, cheaptickets.com/App/...?keywordPIB=fargo,north+dakota&hotelChains=AA. They all look to me to be tracking URLs, easy for a human eye to detect.
I wouldn't of blog this but there is also a WebmasterWorld thread with a different user complaining about a similar issue.