Unintended consequences of Ajax
One of the wonderful side-effects of the adoption of Ajax architectures for Web applications is the immense server-side API clean-ups. The server now has to support properly partitioned, modalized, and layered, interfaces which consume and emit XML. The absolutely wonderful aspect of this is the efforts are coming from within in order to support actual user demands rather than being forced from without due to compliance with some standards body or set of government regulations.
In the future, I believe that the true impact of Ajax will be felt more with easy server-side integrations and service federations rather than gee-wizzy new GUI widgets. The pressure presently coming from the new front-end interaction models will help to crystalize these APIs into gems of cohesive simplicity enabling emergent functionality at incredibly lowered integration costs.