This *is* google releasing to the public. They bought up Blogger, they own Orkut - they have their eye on all of the semantic web stuff, ie FOAF.
The internet is gossip powered: RSS and blogging are two of the more popular fads right now. Your journal of your geekishness, indexing and pointing out what you find of interest on the internet. People you talk to or meet read your journal and get a personalised wandering through the internet - as you.
Social networking - telling your friends - is indeed a clever marketing ploy - making the end user feel incredibly important -> "I know someone that gave me Gmail" is like saying "I know someone who consorts with celebs" - there's a feeling that your only *this* far away from someone important.
There's a lot of that stuff in blogging: I can leave comments for the internet explorer 7 developers on their personal blogs, I can read about what google is doing in their personal lives - the rich and the powerful are now only a google search away.
And.. Watchdog, oh my god do you *not* pay attention to the internerd :S as if you've not heard of gmail!
Finally: Outta invites people, those lucky ones that got em from me, pass em on just as freely! Enjoy.