First off they are now collecting tax information so they can report your earnings to the Fed. This is no supprise to me, for more info on that part see the post here.
Additionally they are now offering an alternate method of showing ads when targeted ads are not available. IE instead of showing PSA they will show a banner or ad of your choise.
Second, we've introduced an 'Alternate Ad' feature to your
account. This new feature allows you to monetize your ad space in
the event that Google is unable to serve targeted ads to your
page. From the 'Ad layout code' page, enter the URL of a static
image, clickable image, or ad server, and AdSense will load your
ad instead of Public Service Ads (PSAs). Should you choose not to
specify your own ads, PSAs will continue to be served to your
For more information on the new 'Alternate Ads' feature and how
to take advantage of it, please refer to the AdSense FAQ at:
Oh and there is also a change in the TOS so when you login you will have to review and approve the changes.