Michael Schwarz has built an amazing library (AJAX) to allow server-side processing without requiring postback.In fact his framework exposes a functionality to asynchronously sending and receiving HTTP Requests and HTTP Responses to and from the server. I guess Google suggest and Google map are both using the same technique. I'm sure that AJAX will change the asynchronous design patterns and will have a great impact on separating tiers in application architecture soon. Here is the definition of AJAX I found in Wikipedia.
