This is only one of the cool additions to Hardy Heron, the latest version of Ubuntu to come out.
Other new features include Firefox 3 beta, modified in Hardy for stability, better hardware support, upgraded versions of all applications, Transmission BitTorrent client, and a nifty new wallpaper!
You can now also try Ubuntu inside Windows like a regular application. No need to partition, and no harm to your system. Give it a try!
For more details, check out the Ubuntu website.
Update: The new File Operations manager now also offers the “merge” feature when overwriting folders. In Windows, if you choose to overwrite a folder, it will blindly overwrite all of its contents as well. With merge, you will have the option of confirming which files inside the folder will be overwritten. Cool!