The latest version of the Java Pet Store Reference Application includes AJAX. This allows enterprise java developers to ease into the AJAX world via an existing comfort zone -- the Java Pet Store.

Here are two AJAX recommendations for the enterprise java developer (from the Java One talk - TS-1615 Javaâ„¢ EE 5 BluePrints for AJAX-Enabled Web 2.0 Applications (Details | Slides)).

• Adopt a library and don't try to re-invent the wheel
  • Prototype
  • RICO
  • Script.aculo.us
  • Dojo
  • Zimbra
  • Google Web Toolkit
• Use xml for structured portable data, use plain text for when injecting content in the HTML, use JSON for direct representations of objects

For more detail, view the slides.