Yahoo spoke for an hour, and I think surprised many people.  Topics covered;

• the value of social search – example, yahoo answers – 10 million answers in 5 months
• how customers rely on friends and family as part of the purchasing process
• examples of financial services opening up their brands to social computing

• Visa – Lifetakes
• HSBC – pointofview.com
• I would also add to that, Wells Fargo – In History

They spoke of the engagement metric, and the relevance of the portfolio of considerations, used to understand how customers get to their decision

the value of product comparison – Progressive Insurance keep customers on their site, by this method.