Google AdSense as always keeps on adding new policies to their already heavy user policies. This time around there are some interesting changes to their policies with regards to ad placements.
The first interesting change is no ad units under section headings that imply ads are not ads. According to the policy such formats may mislead a user that the ads are part of the post. This change affects the hugely popular format used by most blogs wherein the ads are directly placed beneath the title before the content starts. Check out the screenshot below to look at the format of the ads.
Google AdSense,AdSense Policies