The client runs on your desktop and checks a folder in your home directory every so often for updated files. When it sees that a file has been updated, it will automatically sync it up to a server. I wonder what would happen if you logged off in the middle of a sync? I have not tested that out. So far I have been only using it to save documents and a few work files. I was able to sync them up from my Ubuntu machine at home, and upload the files. The next day at work, it was an easy retrieval, even from a Windows machine.
There seems to be no equivalent to a client that would run on a Windows machine for automatic file syncing. That probably would be the next step.
If I stick to straight documents, I seem to get the same functionality out of Google Docs. But Google Docs is a manual process. My guess is that some sort of file syncing process will arise out of the new Chrome OS. The possibilities are there.