Penguin has launched a blog site that seeks both reviews and social commentary on their list of over 1,400 classics. You can register to receive one of their titles in the mail and then 'blog' about it on the site. It launched a few months ago but at the moment this interesting experiment looks like a site for reader submitted reviews. There are some comments attached to some reviews but the site doesn't seem to capture the spirit and spontaneity that blogging could engender.
Blogging can be anarchic and to some extent that's what you would want to see from this project: Someone having a conversation with or interaction with a book as they read it. What they feel, what they don't understand, what happened that day in their lives that reminded them of the book, whatever.... We can get a book review from Amazon. I think Penguin should take the shackles off and loosen up.