Yahoo showing Google Adwords links in its SERPS?

What's up?

[mcguffin]

I just ran a keyphrase search for a company name on Yahoo, just to see what pages contained references to the company.

The #1 Yahoo SERP result points to the company's index page, but at the bottom of the result it doesn't list the company's index page. Instead, it lists a Google Adwords tracking url:

www.webmasterworld.com/?referrer=Google.

1. How did Yahoo's spiders pick up the tracking url?

2. How could a Google Adword tracking url achieve #1 rank for a site?

3. Is Slurp clicking on Adsense links somewhere?

Anyone have an idea of what's happened here? If so, please share! Thanks!