I think that social media will become a VERY useful tool when social networks are used to benefit the individual user along with the group (as in business networking, etc.). I see the killer app as an aggregate commerce engine where you can gather together 10 of your friends looking to buy a flat-screen TV and buy them all in bulk at a discounted price, shipped to each separate location. It’s Costco embedded in your social network, and it puts the “social graph” to a practical purpose. The logistics of this may be difficult, but I think it will be inevitable.