...we’re making it faster and easier to restructure your campaigns and build out new ones with the ability to copy and paste in the AdWords interface.

Using copy and paste should be a familiar task. Just select the items you want to copy, then click the Edit drop down button and select Copy (or just hit Ctrl-C/Cmnd-C). Next, navigate to where you want to paste the items. Then click the Edit drop down button and select Paste (or just hit Ctrl-V/Cmnd-V). You can copy keywords, ads, ad groups, or entire campaigns.
Google AdWords Now With Copy and Paste In The Interface [plus.google.com]