Here's a glossary and links to the next generation web technologies and projects provided by Sun. Scroll down to see more detailed explanations of each topic.

Rich Internet Application Technologies

Ajax technologies allow a website to be--or appear to be--highly responsive because of support for asynchronous and partial refreshes of a web page. Ajax technologies also bring the ability to produce Rich Internet Applications within a browser environment.
Included in the Sun Web Developer Pack.

jMaki is a lightweight client/server framework for creating JavaScript-centric Web 2.0 applications. The jMaki widget model, based on the HTML, JavaScript, and CSS standards, can be used to easily wrap widgets from any given toolkit, or even create your own widgets. jMaki also allows widgets to use publish/subscribe event services as well as XMLHttpRequests. In addition, jMaki widgets can effortlessly communicate with a variety of server-technologies including PHP, Java (JSP/JSF), Phobos, and even RESTful web services.
Included in the Sun Web Developer Pack.

Project Dynamic Faces combines the power of JavaServer(TM) Faces with the responsive user experience of Ajax to deliver enterprise-grade web applications. Dynamic Faces allows you to extend your Java Enterprise applications into the world of Web 2.0 with minimal developer effort and code modification. Project Dynamic Faces comes with an easy to use JavaScript library that exposes the JSF lifecycle to the web browser, enabling innovative features such as partial or full tree rendering via Ajax, dispatching real JSF events from JavaScript, and AjaxZones.
Included in the Sun Web Developer Pack.

Web Scripting Technologies

A scripting language based on the concept of prototype-based programming, JavaScript is best known for its use in websites (as client-side JavaScript), but is also used to enable scripting access to objects embedded in other applications.

A declarative, statically typed programming language, JavaFX includes first-class functions, declarative syntax, list comprehensions, and incremental dependency-based evaluation. This scripting language has the same level of IDE/tool support that Swing programmers are familiar within Java technology: an editor with code completion, refactoring, a Javadoc-like documentation tool, a source-level debugger, a profiler, and ultimately a visual builder. See more.

(Hypertext Preprocessor) is a reflective programming language originally designed for producing dynamic web pages and remote application software. PHP is used mainly in server-side scripting, but can be used from a command line interface or in standalone graphical applications. Textual User Interfaces can also be created using ncurses.

Ruby is a reflective, dynamic, object-oriented programming language. It combines syntax inspired by Perl with Smalltalk-like object- oriented features, and also shares some features with Python, Lisp, Dylan, and CLU. Ruby is a single-pass interpreted language. (From wikipedia).

JRuby is tightly integrated with Java to allow the embedding of the interpreter into any Java application with full two-way access between the Java and the Ruby code. It's designed to work as a mixed-mode virtual machine for Ruby, where code can be either interpreted directly, just-in-time compiled at runtime to Java bytecode, or ahead-of-time compiled to Java bytecode before execution. The JRuby language is extraordinarily well suited for building database applications or manipulating data.

Phobos is a lightweight, scripting-friendly, web application environment running on the Java platform. It comes with a set of plugins for the NetBeans IDE, including a fully-featured debugger; wizards to help you get started faster; a palette of Ajax widgets that can be dropped on a page, and the ability to generate a standard web application for deployment on any servlet container or Java EE application server. Currently, the primary language supported by Phobos is JavaScript. By leveraging JavaScript on the server, Phobos allows developers to use the same language on the client and server tier of a web application, eliminating the impedance mismatch that characterizes other approaches to Ajax.
Included in the Sun Web Developer Pack.

Web Interface Technologies

The Web Application Description Language (WADL) provides an XML description of HTTP-based Web applications. An number of Web-based enterprises use HTTP-based applications that provide programmatic access to their internal data. WADL provides tools to generate client side stubs from WADL files, which may in turn be used to describe HTTP-based functions that external applications may call upon.
Included in the Sun Web Developer Pack.

The RESTful Web Services API provides a programming model that enables developers to rapidly build Representational State Transfer (REST) web services using Java. The API and programming model encourage the use of the REST architectural style, as well as the unencumbered use of HTTP 1.1. WADL files are automatically generated to describe services built using the API.
Included in the Sun Web Developer Pack.

Web Application Architectures

Comet is a web application architecture in which a web server sends data to a client program (normally a web browser) asynchronously without any need for the client to explicitly request it. It allows creation of event-driven web applications, enabling real-time interaction otherwise impossible in a browser. Though the term Comet was coined in 2006, the idea is not new, and has been called various names, including server push, HTTP push, HTTP streaming, Pushlets, Reverse Ajax, and others. (From wikipedia.)

The Grizzly architecture provides is an HTTP Connector based on NIO (New Input/Output) shipped in GlassFish and was designed to work on top of the Apache Tomcat Coyote HTTP Connector. Get more info.

Web Syndication Technologies

ROME is an API for parsing and generating all forms of RSS and Atom from Java. The project's flexible architecture makes it easy to customize the parsing process and to support popular RSS/Atom feed extensions. The ROME project also supports sub-projects that enable efficient feed fetching and caching feed persistence, Atom protocol and numerous extension modules including GeoRSS, GData and iTunes RSS.
Included in the Sun Web Developer Pack.

Other

A mashup is a website or application that combines content from more than one source on the Internet into an integrated experience.