I think it's analogous to TV networks, actually. In the 1950s, there were only 3 TV networks: ABC, CBS & NBC. Who needed more? Now there are hundreds of networks, aimed at all kinds of niche audiences.

There were also "portals" in the 1990s.. Yahoo, AOL, etc.... how many of those still exist as "portals"? 

Maybe social networks will go the way of online portals -- and become something totally different. 

I, for one, would like to see fewer websites that require a login to be useful.

I expect most people use LinkedIn for work and Facebook for everything else. A relatively few power users use other social networks for a variety of reasons, having to do with content, capabilities, and connecting with people who only use that network 

Do you envision a time when people will only use one social network? Or do you think it'll continue to be a pathwork quilt approach, where people use a mix of different social networks for various tasks/reasons?

Google+ isn't just a social network... but then neither is Facebook. Facebook is also building  out a bunch of services that its social functions will sit on top of. Facebook has photo sharing features that Google's Picasa/G+ services are not quite as good as. Facebook also has an email service, but it's much worse than Gchat/Gmail. Eventually, I think a lot of these extra services will become almost standardized across social networks.

Twitter seems to be the odd one out since it doesn't really do search very well... maybe not yet?

That's a good point: People like what they like, not because they're first or second usually. I have always wondered why car-makers always say they're the best-selling car; I don't want a car that everyone else has, necessarily! Yawn. But of course, with social media if you don't have critical mass, don't have a lot of users, it'd be like throwing a party and no one showing up (or leaving early, MySpace).

"The first four died from eating poison mushrooms. The fifth one died from a blow to the head."

"A blow to the head? What happened?"

"He wouldn't eat the poison mushrooms."

Old joke. 

Indeed. Burning bridges is never a good idea. Leave your employer on good terms if you can -- and if you can't, don't settle for burning the bridges. Carpet-bomb them. :)

mhhfive - Good point. I don't drink Coke OR Pepsi; I like Diet Dr Pepper. 

Google+ isn't just a social network. It's a social layer that connects all of Google's services. In that respect, it's a fundamentally different animal than Facebook, Twitter, LinkedIn, etc. 

Maybe Google will try to adopt the "Avis" slogan of "we try harder" because they're #2... :P

It doesn't really matter to most people who is #1 or #2... as long as the product delivers what the users want. If Coke or Pepsi switched places in popularity, would any consumer really care that much?  McDs vs Burger King?  NBC vs CBS vs Fox vs ABC? (I don't even know which network is ranked higher, honestly)

Someday there will be as many social networks as there are cable networks.. and each will serve their communities for certain things (eg. friends, dating, career networking, etc). And no one will really care who is #1 or #2.

And takes out a large life insurance policy on #6, of course!