[cryos]

Except for the obviously flaw where Gmails isn't as popular as you suggest. Having a lot less users than either Yahoo mail or Hotmail. Heres two links to verify that statement (second from google itself):

http://www.campaignmonitor.com/stats/email-clients/

https://lh6.googleusercontent.com/-uhu-fZwXC60/Th6LbbZFv_I/A...

I'm not saying change isn't coming. I just don't think a Google social network will be it. Hell even there 18 million user announcement is quite average... thats under 10% of gmail users.

Considering MS has been spotted toying with implementing Social networks directly in Windows 8 (and with their share of FaceBook + Windows Live + Desktop OS we are talking massive users base).

A decent implementation could destroy all competition. The only ray of light there is MS history of failure.