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.
http://groovy.codehaus.org/Groovy Programming Language
Growing article, with links to many related topics. Wikipedia.
http://en.wikipedia.org/wiki/Groovy_programming_language
Java Community Process Program: JSRs: Java Specification Requests: 241
Groovy standardization page.
http://www.jcp.org/en/jsr/detail?id=241
Groovy: The Birth of a New Dynamic Language for the Java Platform
Brief summary of ideas behind Groovy; by James Strachan, Radio Userland.
http://radio.weblogs.com/0112098/2003/08/29.html
JSR-241: Groovy � A New Standard Programming Language for the Java Platform
Long analysis and critique; Richard Monson-Haefel's Weblog.
http://weblogs.java.net/blog/monsonhaefel/archive/2004/03/jsr241_groovy_a.html
G$D/Groovy: Index
List of Groovy posts. O'Reilly ONJava Weblog.
http://www.oreillynet.com/onjava/blog/2004/10/gdgroovy_index.html
Groovy, Java's New Scripting Language
Description, with text, code samples, screenshots. O'Reilly ONJava.com.
http://www.onjava.com/pub/a/onjava/2004/09/29/groovy.html
JavaOne 2005, Day 1: It's a Groovy Day
Substantial report on Groovy from first day of conference: text, code samples.
http://www.artima.com/weblogs/viewpost.jsp?thread=116723
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.
http://www.grails.org/
Groovy: First Contact
Review, by enterprise developer Mike Spille. TheServerSide.com, Enterprise Java Community.
http://www.theserverside.com/tt/blogs/showblog.tss?id=GroovyReview
Advanced Groovy
Slide presentation, given to Denver Java User Group, JUG; by Rod Cope, of OpenLogic, Inc.
http://www.openlogic.com/downloads/OpenLogic.AdvancedGroovy.pdf
Groovy = Java + Ruby + Python
Slide presentation, given to Denver Java User Group, JUG; by Rod Cope, of OpenLogic, Inc.
http://www.openlogic.com/downloads/OpenLogic.JSRGroovy.pdf
Groovy Wish List
Criticism, mainly of "." and "->" operators. Otaku, Cedric's weblog.
http://beust.com/weblog/archives/000102.html
Java 7 aka Groovy 1.0
Shows how some features proposed for JDK 7 are already in Groovy, maybe in better forms; with reader comments. Java Thoughts and Other Stuff.
http://javajmc.blogspot.com/2007/01/java-7-aka-groovy-10.html
Groovying at ACCU 2006
Page on presentation given by Russel Winder at ACCU 2006 conference: brief comments, links to PDF slides, source code.
http://www.russel.org.uk/blog/2006-04-24-11-59
