The web has evolved. It has matured.
Web frameworks are now a commodity and ajax went from being a cool novelty to simply standard. This is all good since developers can now focus on what really matters: “desktop collaboration”. Social networks focus on collaborating with others. That’s great and all, but now we need web apps to collaborate among them. For instance in my Mac I can write an email in Mail.app and add pictures from iPhoto by brining up the media inspector. This type of desktop collaboration is easy on a Mac since Cocoa does all the heavy lifting for you. Hopefully OpenSocial will evolve to do something like that. It can be done now through APIs, and REST services but never like a Mac. It will someday be like that. Where I can easily add a picture from my flickr account to my gmail message.
It’s funny how things evolve: Terminals to PCs to Web services (terminal-like).