Jeremiah Owyang is a highly respected social mediatician (I just coined the term).
Although the source link below is a bit over a month old now, it has some insightful data.
You cannot ignore social media—the numbers (and trends) do not lie!
From Jeremiah’s blog post:
If you’re seeking stats from 2008, I’ve compiled them on this similar post of 2008 social networking stats.
Stats are important –but on their own, they don’t tell us much
Stats on social networks are important, but I’m going to need your help in creating a community archive, can you submit stats as you find them? I’m often asked, “What are the usage numbers for X social network” and I’ve received considerable traffic on my very old post (way back in Jan 08) of MySpace and Facebook stats, even months later. Decision makers, press, media, and users are hungry for numbers, so I’ll start to aggregate them as I see them.
How I interpret stats
Numbers don’t tell us much without insight and interpretation, in fact, you’re going to see conflicting numbers of usage from many of the agencies and social networks themselves. The key is to look at trend movements, don’t focus on the specific numbers but the changes to them over time. I put more weight on active unique users in the last 30 days vs overall registered, in fact, the actual active conversion rate will often range from 10-40% of actual users sticking around and using the social network, so don’t be fooled by puffed numbers. No single metric is a good indicator, you have to evaluate the usage from multiple dimensions, so you also have to factor in what are users doing, time on site, interaction, and of course, did they end up buying, recommending products, or improving their lives.