If you login to your AdWords account, go to a campaign and click on the arrow down near the tabs, you will find a new option. The new tab option is named "dimensions" and provides a different look at your AdWords charts.
The reason for this change is because they are dropping the reporting section and adding more reports and filters to these campaign screens.
Here are pictures:
Personally, I am a fan of putting reporting directly in the interfaces you use most often.
Forum discussion at Search Engine Watch Forums.