There is some excitement with this rich client-side engine that mediates data interchange rather unobtrusively in a browser frame, catching input and sending it to the server, catching the results and more gracefully rendering the results. This is a step up from the staccato jerks of normal HTML page interaction, providing a smoother transition between almost unobtrusive loads.
Google's Maps or Google Suggest (see how the search narrows as you type) are examples of using this technology. You program this with things like ECMA Script .
Ajax is a composition of standards and technologies that includes:
* data interchange using (surprise!) XML
* data manipulation with good old XSLT
* asynchronous data retrieval using XMLHttpRequest
* standards-based presentation (XHTML and CSS)
* dynamic rendering and interaction using a tree structure similar to a Document Object Model
Adding this layer of mediation to the presentation layer of your SOA will further enable Web services consumption: