Earlier, if you right-click the Dropbox icon on your notification area, you’ll get a small menu. It’s a normal system menu. But they are experimenting on replacing the default OS menu with their own customized version!
Check the above screenshot… The new popup menu will have more features (like the recent files) and will be more user-friendly. In the future, interacting with Dropbox service is going to be much more interesting and easy. This is still an experimental feature. You can test it by using the test build which you can find from their forum. But do not use it if you don’t know what you are doing!