Personally, I don't consider semi-anonymous public discussion forums such as this to be "social media". I consider social media to be private/semi-private communications between groups of people who know each other personally, perhaps because this format has existed for quite some in the form of Usenet and BBS, and they have never been described as "social media" like facebook & co. has.
I also consider the eetimes.com comment forums to be social media -- and I think it's valuable for engineers and others who work in our industry.
But I have one gripe -- the comment forums are not accessible from the EE Times mobile app. Maybe someday UBM can get some people to work on that!
It will be interesting see what engineers have to say about the likes of LinkedIn, Twitter, Facebook etc.
The key question will be the one about time spent on all social media.
Will it be a normal distribution with a peak around "less than one hour per day" or bimodal with peaks at the two extremes representing the "SM is useless" and the "addicted" camps?
Also does commenting in this forum count as part of social media...or is it just internet browsing?
If you use social media (which I'll define as "Facebook" for this discussion) for what it was originally intended -- to keep up with actual friends -- then it's fine. If you and your friends do fun and interesting things, then it's great. If your friends are boring, then it's boring.
For business use, I don't much see the point of Facebook or (especially) Twitter. Do I "like" Xilinx (for example) on Facebook? No. Why not? Because if I want or need information from Xilinx, the first place I go is to their website. And then I call my local FAE. The Facebook updates from Xilinx and others are shorter versions of e-mail updates they send out regularly, so it's redundant. OK, maybe users can post snarky comments to the Xilinx updates, but one suspects that they'll be deleted for the obvious reasons.
Now if you expand your definition of "social media" to include things like vendor discussion forums, user-to-user professional forums and (showing my age) Usenet newsgroups, then, yes, social media are very valuable. (Except for Usenet, where every discussion devolves to a flame war.) User-to-user discussions, where those users are serious, can be very informative, and you can learn a lot of things just by browsing. What you read might not be useful immediately, but you remember certain techniques which might be very helpful in a future project.
eevblog is one of the only ones I enjoy, but I don't use it in a professional community. One thing that wasn't asked of respondents is if they use Manufacturer's forums. And there may be a distinction between "using" as in looking passively and "using" as in participating.
I was not fond of social websites until I became involved with Element 14. There I found a very informal society of engineers, scientists and technology enthusiasts. The exchanges were very stimulating and fun to explore. I would still not run out and just join any social website, but when I found one that responded to my interests, I found I had a good time talking with like individuals worldwide.