It looks like LinkedIn has found a way to make itself relevant for day-to-day use... The Amazon Readling List provides a way for you to post what you're currently reading, want to read, or have read. You can also see the contents of other people's reading lists--in your network, in your industry, or all recent updates. Your reading list will automatically appear on your LinkedIn Home and Profile pages.
So far, I only have one book listed. I'll probably start adding to this reading list from my Safari bookshelf list, and all the various other lists that I've been compiling over the last couple of years.
You can get to my LinkedIn profile at http://www.linkedin.com/in/twilliampowell