How to measure the success of Social Media has been a huge problem in this industry for quite a while. There is a consensus that the number of fans/likes on Facebook or of followers on Twitter is too weak an indicator, but the alternative metrics are still rare: No golden standard has emerged yet.
This presentation by 22squared on Return on Investment (ROI) in Social Media is the best I’ve seen in a long time. One of the few really good ones, really, as it backs up the main claims with data. Since you read this blog, the core finding won’t really be a surprise to you: Social Media engages customers and stakeholders, leads to interactions and eventually even to increased sales. (The latter part being the least important here.) It’s certainly good to have a decent study to back this up.
The key idea is to factor in non-financial benefits of Social Media engagement, too: Return on Investment = Return on interaction + Return on influence.