Reports are coming from the forums that Google has updated the AdWords interface. The most comprehensive documentation of the changes made are at WebmasterWorld. Basically, Google placed most of the features in additional tabs. When you login to your account and drill down to a campaign, you may notice a little balloon pop up on the right hand side. Under the ballon, which introduces the new tabs, include three tabs, named "Summary", "Keywords," and "Ad Variations." Here is a screen capture.
The AdWords Support page has detailed information about the new tabs. It reads;
Your account statistic tables are now presented on separate tabs, which can be found along the upper right edge of the table. These are the available tabs:
* Summary displays the performance totals for your Ad Group. * Keywords shows you how individual keywords are performing, and allows you to add new keywords or edit existing ones. This tab appears only in campaigns with keyword-targeted ads. * Sites shows you how your ad is performing on individual sites you have selected. You can add new sites or change your bid for existing ones. This tab appears only in campaigns with site-targeted ads. * Ad Variations displays all the ads you have created for this campaign. You can add, edit or delete ads here. At any time, you can view the information from all your tabs on a single long page. To do so, click the View all tabs at once link below the display table. To return to the tab view, click Condense tables into tabs.
There are other changes, you can read at AdWords.