SkyDrive is live with OneNote Sync, you can now go to Office.live.com and start upload your OneNote files. Office Web Apps on SkyDrive are available free for personal use.
When you creating New Notebook in OneNote 2010, you can now save it to SkyDrive directly. To get start, you will need to have a Windows Live ID, and sign in when you are asked to. Notebooks will be automatically synced among different OneNote clients if they are online.