My hat is off to Microsoft. The company is the first of the major ISPs to move toward offering a true "unsubscribe button" in place of the ubiquitous "spam button" (see my entry on this last year).
The idea has taken a while to see the light of day, and Microsoft's initial foray is a pilot program, but it's definitely progress no matter how you look at it.
Here's why this is important. The main characteristic that an ISP considers when deciding whether to block a sender's messages is the number of complaints it receives. Complaints almost universally are determined by the number of times ISP subscribers hit the spam button in their email programs. The problem is, recipients have discovered that pressing the spam button usually results in being removed from a list -- even lists they've subscribed to. As a result, ISP subscribers have started pressing the spam button for any message they don't want, even when they know the message isn't unsolicited (spam). By replacing the spam button, or adding a second button, subscribers can now be more specific about what they want done, and ISPs can get much more accurate information about which senders they really want to put on block lists.
Check out http://directmag.com/disciplines/email/microsoft_unsubscribe/ for a good article on Microsoft's recent pilot.