Although the official announcement will be made Thursday by John Lam at the O'Reilly Open Source Convention in Portland, Oregon, a Microsoft spokesperson did confirm to BetaNews this afternoon that IronRuby - its .NET-centric version of the open source scripting language Ruby - is now publicly available.

As Microsoft development general manager Scott Guthrie and lead IronRuby developer John Lam both stated on their respective blogs today, IronRuby and its associated libraries will be offered to the collective development organization RubyForge.com, for posting and public contributions next month.

Guthrie said that some of the critical libraries necessary for fully implementing even an alpha of IronRuby have yet to be implemented, thus the version for download - currently hosted by Lam's own site - is being considered a "pre-alpha" version.

IronRuby will join IronPython in making use of a new .NET component called the Dynamic Language Runtime (DLR), whose purpose is to enable lightweight language implementations for applications that don't require compilation. Instead, so-called dynamic languages use adaptive, flexible code for use in rapidly changing environments such as Web-based meta-applications, especially those that involve more than one server.

In typical object-oriented languages, structures are developed that represent states of data and the methods that process and change that data. In a language like C++, those structures are classes. For statically-typed languages, classes are set in stone.

But for Ruby - and thus, in turn, IronRuby - not only can classes be modified on the fly, but other classes that inherit their data and functions (what Ruby calls "descendants") can be modified as well. Ruby expects that it is learning functionality as it goes along, and that nothing is impervious to modification.

In his blog post today, Lam claims performance tests of IronRuby method calls yield faster observed times than for the most current stable release of Ruby for Windows (1.8.6). Lam's close involvement with the Silverlight project may also fuel speculation that Microsoft's developers may be planning to pair IronRuby together with Silverlight, as a display engine.