There's interesting blog post about social media and consumer behavior over at Mashable.com that ponders the impact of companies plunging forward with web 2.0.  Do you consume social media or does social media consume you?  Here's a snipit:

At this point much of the traffic is being driven by the early adopters who have been using services like Twitter since it started but slowly more and more regular web users are discovering it – and others. As well, corporations are dipping their toes into this new social media sea; therein lies the one thing that could really push social media beyond just being a niche sector.

I buy the economic argument -- when companies realize the return on investment of marketing dollars spent on social media they will flock to it.  I'm not so sure that big corporations know how to get it right, however.  We've seen many attempts to jump on the user-generated-content bandwagon fail and even backfire.  It's still going to be the information service companies that will be most adept at throwing snowballs down the social media mountain.