I'm already a big fan of the 'Share a Page' Google Reader Bookmarklet.
Sure people can fake out what the page actually says by re-writing the summary of the page but aren't these people supposed to be your friends? Try that once on me and you're dumped.
I share discoveries a lot by RSS. It is simply wonderful to be able to share single pages; suddently my daily Mixx summary is worth twice as much as it was worth before.
I also have a diverse group of friends. What I'd really like from Google Reader is a tag/label based share system. I want to be able to share some content with people and mark it 'search' so it only goes to the people interested in 'search'. I'd like to be able to share different content with people and mark it 'gaming' so it only goes to my geeky RPGamer buddies!
Increasingly Google Reader is the centre of my universal. My web comes to me in RSS streams and I manage all that via Google Reader. I love the way I can handle the incoming data - I just want more control on my outgoing data!