Charles Nutter and Thomas Enebo have made it clear that being taken on by Sun means they can work on jRuby all the time and will not mean any changes, particularly to the three way CPL/GPL/LGPL licence.
The pair will officially join Sun later this month. According to a statement by the pair, Sun is interested in the project to make sure that it is accessible to its community of Java developers. There is an outside chance that Java might prove to be an attractive deployment option for some Ruby applications.
It is also an indication that Sun is starting to think that the Java platform is a bit bigger than just the core language.
More here. µ