I don't know when we might have a sample made available for this, but to give you a starting place look for "batch update" topics in the help and in our KB as well as in the forums.  There's the UpdateRowBatch event which will be what you'll want to handle.  With the batch events, all updates (adds, removes, updates) will be batched until something forces a postback to the server (this could be an async callback in an UpdatePanel as well).  At that point, your batch events will fire, giving you a chance to handle them.  The complexity comes however when you need to postback to the server before you actually want to save the data to the database.  To solve this problem, you'll want to create your own internal "queue" of updates, to be executed only when the "save" process is invoked.  You can store the queue in session state, in a SQL server, etc.  Anyway, I hope this can help you get started.

-Tony

Actually,

I would like that this be a disconnected environment (if it could be with a SQL dataSource it would be great). The datasource would only be updated when we click a save button......

thanks