Groovy:Object-oriented language alternative for Java platform; Java-like syntax, dynamically compiles to JVM bytecodes; compiler can emit bytecodes, or can be used dynamically for scripting; has features not in standard Java, from Python, Ruby, Smalltalk. Open source.
Exploring the Mysteries of Groovy Properties: Review and tutorial. Pyrasun, The Spille Blog.
Feeling Groovy: Informal introduction to a proposed addition to the standard programming languages for the Java platform. By Andrew Glover. IBM developerWorks.
G$D/Groovy: Index: List of Groovy posts. O'Reilly ONJava Blog.
Getting Groovy without the Bad Clothes: Tutorial introduces dynamically-typed scripting language for Java Virtual Machine, shows how to create a first script. scratchProjects.com.
Grails: Web application framework, Groovy version of Ruby on Rails, to use in Java development. Can be standalone system that hides all configuration details, or integrates Java business logic. Simplifies much work, appeals to range of developers not only Java. Open source.
Groovy Programming Language: Growing article, with links to many related topics. Wikipedia.
Groovy Wish List: Criticism, mainly of "." and "->" operators. Otaku, Cedric's weblog.
Groovy, Java's New Scripting Language: Description, with text, code samples, screenshots. O'Reilly ONJava.com.
Groovy: First Contact: Review, by enterprise developer Mike Spille. TheServerSide.com, Enterprise Java Community.
Groovy: The Birth of a New Dynamic Language for the Java Platform: Brief summary of ideas behind Groovy; by James Strachan, Radio Userland.
Groovying at ACCU 2006: Page on presentation given by Russel Winder at ACCU 2006 conference: brief comments, links to PDF slides, source code.
Java Community Process Program: JSRs: Java Specification Requests: 241: Groovy standardization page.
JavaOne 2005, Day 1: It's a Groovy Day: Substantial report on Groovy from first day of conference: text, code samples.
JSR-241: Groovy � A New Standard Programming Language for the Java Platform: Long analysis and critique; Richard Monson-Haefel's Blog.
Practically Groovy: Functional Programming with Curried Closures: Enhance standard closures with Curry method, invented by Haskell Curry; was in Groovy before JSR compliant releases. By Andrew Glover, Ken Barclay, John Savage. IBM developerWorks.
Practically Groovy: Groovy's Growth Spurt: With release of a JSR-241 compliant parser, changes to Groovy syntax were formalized. Treats most important changes to syntax, shows handy feature not in older Groovy. By Andrew Glover. IBM developerWorks.
Practically Groovy: Of MOPs and Mini-languages: Primer on Meta Object Protocol, an old-is-new way to build programs, languages, and programs as languages. By Andrew Glover. IBM developerWorks.
Practically Groovy: Smooth Operators: Java bans operator overloading. Groovy does not. Learn everyday uses of 3 types of overloadable operators. By Andrew Glover. IBM developerWorks.
SimonPeter.org: Groovy: Much information, tutorials, home of 'Learning Groovy': cross between tutorial and list of lessons learned; in the style of Kernighan's and Ritchie's book 'The C Programming Language'.