When I upgraded to Ubuntu Karmic Koala (9.10), I had a cursory glance over the Ubuntu One and did a setup. It basically was supposed to provide a syncing mechanism of your local files with storage in cloud (Ubuntu One servers).
I could not get it working then. But over the past few days, I had been travelling around and realized that I would not be carrying my laptop around always. And I would require access to some of the files no matter where I was.
The solution is quite simple. Remove the files in ~/.config/ubuntuone folder and restart Ubuntu One client - right click on the icon and select Quit; and then start it again from the Applications menu.
After that, it synced and uploaded all the files in a jiffy!