I see the JRubyists have shipped JRuby 1.1. I increasingly think JRuby is interesting and important as a test case, even if you don’t happen to care in the slightest about Ruby or Rails.
JRuby 1.1 Goodness · For those of us who do care about Ruby and Rails, 1.1 is good news because it’s a whole lot quicker and more robust than 1.0. One of the biggest pieces of goodness is Marcin’s incredible feat of porting Oniguruma, the next-gen Ruby regexp engine, to Java (I think the Java people ought to look seriously at adopting it in a future Java SE release).
Important, Why? · Because JRuby is really a proof point for the notion of multiple languages sharing a VM. The only other serious commercial move in that direction is Microsoft.NET, and it really only has 1½ mainstream languages: C# and then VB.NET, which is highly discontinuous with the decades of Visual Basic history.
[Update: In the comments, I’m getting heat from people pointing at Jython, IronPython, and so on. I know about those, but my perception is that the JRuby/Rails combo is getting commercial uptake faster than any of those have.]
JRuby, on the other hand, is a no-compromise attempt to maintain full compatibility with a language radically different from Java on a platform whose raison d'être has for over a decade been running Java programs.
The reasons why in theory JRuby ought to be interesting to both communities, Java (they get metaprogramming and Rails and block-based goodness) and Ruby (they get oceans of APIs, servlets, and a route around IT bureaucrats), are pretty compelling. And despite JRuby’s relative youth, we’re seeing the first wave of commercial production deployments. So the experiment as to whether the advantages in theory play out in practice is well and truly under way.
If it can be done, its importance as an existence proof is profound, and I would expect the ratio of the number of popular VMs to the number of popular languages to decline rapidly from its current value, which is very nearly 1.
If the JRuby project disappoints, it won’t prove that sharing VMs among languages is a lousy idea; but it will be, at best, disturbing evidence. Me, I’m optimistic.
PostScript · There was a flurry of griping today on Twitter: Apparently the RailsConf 2008 program contains exactly zero JRuby: no tutorials, no sessions. Frankly, this seems deeply weird to me: from the Rails point of view, there are going to be quite a few scenarios where you might want to consider deploying into Javaland, just as a practical matter.
However, I’m glad to see that the IronRuby Microsofties are going to be presenting; I think having Rails on .NET is going to add some interesting new flavors and spices to the rich red Web-flavored stew.