Open Dylan is ex-Harlequin Dylan, ex-Functional Developer - an integrated environment for Dylan programming and a library of various classes for different purposes - open-sourced some time ago and now available as the first beta for download for Linux and Windows.
I would prefer if Apple would release Apple Dylan, because its development environment was really light years ahead of everything else on the market, but that will probably never happen - rather there will be an OS X version of Open Dylan. Also quite nice.