Google and Comcast partnered together trying to buy a minority stake in Time Warner's America Online. AOL, who is under major pressure, has previously been talking to Microsoft over a possible combination of AOL with the MSN online service. This would be a major blow to Google because AOL uses both Google ads and search results on their search engine. AOL receives 8% of internet searches.
Later on Yahoo decided to consider buying a stake in America Online, joining Google/Comcast and Microsoft. Microsoft needs that 8% that goes to Google now, so that they start to make their search engine popular. Microsoft also has it's own Pay Per Click program coming out soon, so AOL is needed if they want to move forward in the search engine war.