Principles of Rich Web Applications
I think these are great ideals to strive for, but they seem lower priority than a couple things that they can get in the way of if you're not careful.<p>First, in your quest to show me the latest info, <i>please please please</i> don't introduce race conditions into my interface.  I don't want to go to hit a button or a key or type a command, and have <i>what that means</i> change as I'm trying to do it.<p>Second, it's often important to me what has happened locally vs. what is reflected on the server (especially if that's public).  Please <i>do</i> update the interface optimistically in response to my actions rather 
than sitting and spinning, but please <i>also</i> give me some indication of when my action is complete.