Yes Ubuntu as in Ubuntu the operating system, there are some things that break the standard...
Ubuntu One is the personal cloud that brings your digital life together, so you can enjoy your content, your way, wherever you are. With our suite of cloud services including storage, sync, sharing and streaming - you have immediate access to your music collection, favorite photos, videos, important documents and more, at any time and from any device.
And It runs on windows and mac, that is what Jorge CastroJorge Castro is talking about.
And in the FAQ it says
We welcome questions about:
Using and administering Ubuntu, including official Ubuntu derivatives.
Running third-party applications on Ubuntu.
Development on Ubuntu.
Services provided by Ubuntu
Some of the "Services" (like ubuntu-one) provided by Ubuntu also run on mac and windows.
