Social Networking Sites 10/15

It's been a long time since I've used any of the referenced social networking sites.  Probably because I value privacy over publicity.  However, I have at a certain point in time used all of the following: Facebook, MySpace, Twitter, and LinkedIn.  I've gathered impressions of each of these and they are detailed below.
I think it's interesting that as new of a concept as social media is, each of the above services has carved out its own niche in society. I think each of them accomplishes their perceived goals reasonably well.  For example, Facebook, in my mind, is the social media platform of choice for connecting friends - just friends.  Although many businesses, groups, organizations, etc. have a presence on Facebook, my impression is that these users should focus on exploiting other services (e.g. Twitter).  As I tweeted on my twitter account, many businesses (large and small) are finding that they can successfully reach their clientele through twitter in real time.  I think that this is something that would be considerably more difficult through Facebook.
The one social media platform that I do currently use is LinkedIn.  Although not extensively, I have had moderate success connecting with colleagues through the service, however, this has yet to lead to any substantial opportunity.  Perhaps I need to further explore these platforms - and I look forward to doing so through CIS3810.