It looks like the new HTML 5 standard will be a huge advance for the Web, particularly the communications component.

WebSockets, Server-Sent Events, Cross-Origin Resource Sharing and Cross-Origin iFrame messaging will dramatically change the web. With WebSockets and Server-Sent Events, you will be able to build true event-driven web applications instead of using polling hacks and two connections. Cross-Origin Resource Sharing will change the face of portals (won't be necessary) and Cross-Origin iFrame messaging will facilitate a huge wave of mashups.

Really cool stuff.