An article in the business section of the San Diego Union-Tribune for Sat., May 5, 2007 had a pretty detailed summary of the recent news that Microsoft & Yahoo are reportedly in close negotiation to work together to combat Google's online advertising leadership.
The article sited the following from a research firm called eMarketer that I thought was interesting. In 2006, for everly $100 spent in online advertising: Google got $25, Yahoo got $18, and Microsoft got around $7. In addition, eMarketer is projecting that in 2007 Google is poised to raise their take of that $100 spent to $32. Wow!