Charles O Nutter is the principal developer of JRuby. He has worked at Ventera, Sun, and now, EngineYard. During his time on the project, he has steered JRuby to its place as the fastest Ruby implementation.
Thomas Enebo has striven since 2003 to make JRuby a piece of software that will capture the hearts and minds of Ruby and Java developers everywhere. He works at EngineYard alongside Charles and Nick.
Nick Sieger is a prolific blogger and programmer who contributes not only to the JRuby core, but also to numerous libraries that Ruby programmers depend on every day in their work with JRuby. He works at EngineYard.
Ola Bini writes software at Thoughtworks Studios, and is the author of Practical JRuby on Rails. He is constantly pushing the boundaries between programming languages.
Ian Dees is the author of Scripted GUI Testing With Ruby. By day, he slings C++, Ruby, LabVIEW, and other languages for a test equipment manufacturer in Portland, Oregon.