This is a super article which outlines how ROI can be empirically measured from a social media marketing campaign.  I think this article and the activity described can be used by most brands.  It would be interesting to hear your thoughts on it.  Blog away!

Also let me know your thoughts on Twitter - it's been on our minds for nearly a year now and I wonder if your thoughts on it have evolved.  Mine certainly have.  I now use Twitter to talk about a card selling business I am trying to expand.  It's interesting to see how brands are using Twitter to promote and sell.