Its like google's CR-48 notebook,
which uses the CHROME OS, which is basically the chrome browser with lots of installable extensions.
In essence, the browser is the only program that runs on the computer, and the computer has very little local (hardware) storage.
everything is stored on your online account and is accessible via wi-fi or 3g/HSPDA data connection.
As said before, this means that anything stored online will only be accessible when connected. Basic functionality is maintained, but is limited.
The benefit is two fold. Lighter and more portable hardware, such as a large screen tablet or laptop which is very thin, due to the lack of need for hardware data storage. Longer battery life overall, and ultra accessibility.
i have an android phone, and as such, any info stored on my google account is automatically transfered to my "cloud" account and is accessible from any device.
....the list goes on..
but i will stop lol