Jean first demonstrated Swiby in January 2007, writing it in pure JRuby. He modelled it initially after JavaFX (then known as 'F3') but knew that there's competitors in Adobe's Flash/Flex/AIR as well as Microsoft's Silverlight. Jean lives in Belgium.
Jean keeps his personal swiby related thoughts here
Paul works for ThoughtWorks in the USA. He's been interested in a builder like language leveraging Swing for web usage for a number of years. In 2004, he started 'Thicky' but is happier with JRuby intead of Groovy, hence Thicky is not developed anymore, and he's on Jean's Swiby project.
Paul's blog has a few Swiby related entries