Just a few days ago, I wrote a blog post defending email. I argued that email is structurally sound because it models how people think about disparate information in their lives. Social streams don't reflect that.
Earlier today, Google unveiled the new Gmail. The most heavily-marketed new feature is automatic sorting by type of email. Effectively, it's automatic intelligent tagging that requires no setup or maintenance. It's quite elegant. For example, all emails containing receipts or product shipment details are automatically placed into a tag, represented by a tab at the top of the inbox. All social-networking status updates, including photos, comments, groups, and more are sorted into a single tab.
Google figured out that the senders were the problem, not the medium. Google altered the medium to accomodate the obnoxious tendencies of the senders.
Google, good thinking and thanks for listening :)