I’ll excerp the main bits:
Manning has Groovy in Action (and soon Grails in Action as well). Apress has quite a impressive cadre of titles, from DGG to Beginning Groovy and Grails, GORM, Grails + Flex, and more. The Prags have Venkat and I (Programming Groovy and Groovy Recipes, respectively), plus Dave Klein’s upcoming Grails title. Morgan Kaufmann has the tragically underrated Groovy Programming.
In terms of online articles, I’ve been writing Mastering Grails for IBM developerWorks for a year and a half now.
I’ve rebooted Andy Glover’s old Practically Groovy series. (BTW, I went back and rewrote every Groovy example dating back to 2004 so that they run under modern Groovy — not as hard a task as you might imagine…) That’s effectively 50-ish new pages of new material each month. (And boy are my arms tired… wink) Those articles are regularly among the most popular at IBM devWorks, FWIW. There’s also the monthly GroovyMag, JavaWorld, http://groovy.dzone.com/, SCADS of personal blogs, the Groovy/Grails podcast from Glen and Sven, and more…
I speak 30+ weekends a year on the NFJS tour talking about Groovy and Grails. That’s in addition to JavaOne, TSSJS, QCON, JavaZone, and a host of others. When I’m not speaking publicly, I’m offering private Groovy/Grails training/mentoring/consulting through http://thirstyhead.com . There are many other folks, like Ken Kousen, smokejumper, SpringSource (natch), who do the same.
Andy Glover’s BDD framework easyb — written in Groovy — just won a Jolt award. Both Groovy and Grails have won JAX awards. There’s Griffon, Gant, Gradle, GMock and many other libraries/ frameworks that leverage the power of Groovy and Grails under the covers.
Companies from Wired to LinkedIn to IBM to SAP to SkyTV to Tropicana to Pepsi to Mutual of Omaha to the (US) National Cancer Institute to many many others without a public-facing website or case study have adopted Groovy and Grails.
The Groovy/Grails community has an embarrassment of riches to choose from. (Apologies if I missed an obvious addition to any of the informal lists I rattled off of the top of my head.) This mailing list alone should be an indication of how vibrant the community is.
A nice follow-up quote from Dierk König:
Unlike other languages, Groovy positions itself as “Java’s dynamic friend” rather than trying to be a replacement.
And a bit more from Russel Winder:
“Groovy, the symbiotic partner to Java on the JVM”. The words “partner” and “symbiotic” are crucial here!
Where you need static type checking and fastest execution performance use Java, as soon as you need any form of reflection or dynamism consider switching that bit of your system to Groovy. This is multi-language programming in a total system context.
Time for you, dear reader, to jump on the Groovy bandwagon. Don’t be afraid, the horses won’t bite!