[mlinsey]

since a lot of people keep gmail open ... Not as common to keep one's facebook page open.

Do you have data on this? I'd think it would be close, if not the opposite.

Edit for clarification:

In my social circles, what you said is probably true, but I know many others use FB messages more than email (any email, not just gmail). Facebook has more pageviews total, and Facebook has probably around 3X as many active users (I couldn't find numbers at the same point in time, Gmail was at around 200 million last November as per the WSJ, Facebook was at 500 million last July and 750 million last week)

Don't get me wrong, I agree with you that G+ notifications in Gmail (and on Google Search!) is hugely powerful, and will mean G+ engagement among its users will stay quite high. But when you talk about "unseating" Facebook, you have to first come to grips with just how entrenched it is, compared to social networks that rose and fell before it. It is so entrenched that Gmail integration alone will not be enough - Facebook is substantially bigger than Gmail.

[ChuckMcM]

You are correct in that I was generalizing when I should not have been.

I've used Google Apps for work and since a lot of communication comes through email that means Gmail is open (or at least getting notifications with the talk gadget). I would not be surprised if you were correct that many folks leave Facebook open all the time.

[riffraff]

it's worse than that: among my non technical friends email is used only for "serious stuff" as talking with teachers (or students, for my friends who teach) and for work. For the others facebook messages have supplanted email.

I am obviously not sure this is a global trend, but I keep using the test "who did you receive an email from, recently, who isn't work or a fellow technical person?". Results are somewhat scary.

[wisty]

Yeah, email is now the snail-mail of the mid-2000s.

[ChuckMcM]

Interesting, this means the spammers will have to change venues to reach that part of their demographic. That should be giving them something to think about.