Google Sharing

I dunno. At my "shared" page I stuck a link to Patrick Altoft's "5 Reasons to Start Using Google Shared Stuff" post, but honestly I don't follow his reasoning. He asserts that getting listed at Google's "Popular" page could be far more important than being listed at Digg or Slashdot.. well, maybe so, but I took a look at that page and had zero interest in following through on anything. Maybe I'm too uncool..
Google's Shared Stuff Help Page invites us to "Take a look at stuff that's shared with you", but isn't very clear on how it got "shared with me" originally. Does that mean someone clicked the Google Share button and sent it to me in email? Well, if that were the case, wouldn't I already know about it? Why would I need that "stuff that's shared with you" page?
Ok, I must be getting really, really old, because I don't grok the point of this at all. Possibly that's because if I have something to "share", I either put it on one of my websites or directly email it to the people I want to know about it. Why do I need Google in the middle of that process??
I guess I'll "share" this after I publish it.. why, I do not know..