This week, Microsoft gave access to the source code of the .Net Framework Libraries, under the Microsoft Reference License. By reading this short license, it's clear that it's far from free or open source: it grants you a read-only access and prevents you from redistributing the software outside of your organisation... Actually, developers of the Mono project (the GPL licensed software providing the necessary software to develop and run .NET client and server applications on multiple platforms) are urged to NOT look at the source code, although characterising Microsoft's move as a trap might be exagerated.

It's worhty to note that Microsoft apparantly has a long history of granting access to libraries' source code.

Although IronRuby could already be downloaded, it is now available on rubyforge, with bug tracking and subversion repository. Instructions on getting the source form the subversion repository are available on RubyDoes.net.

Source:InfoQ

A first version of IronRuby is now available under Microsoft's short Permissive License. More info in John Lam's blog.