Google just released a beta of a new product called Google Gears. They've combined a browser plugin and a javascript API to enable local storage of data so that web apps can work offline. This is similar in concept to Smart Client, or so it seems to me, but with the desktop application replaced by the browser extension an the UI all handled by the browser rather than having the desktop UI installed on the client machine.

So I think for example you could implement something like for a travelling salesman who gets to connect from time to time but is not always connected. You might implement his contacts and product catalog as a web site but when he is disconnected the contacts and product catalog come from a local database via Google Gears. Whenever he connects the contacts and catalog would be updated and any orders he has entered can be pushed to the server.

The developer page for Google Gears is here: http://code.google.com/apis/gears/