Nick — 23-Jun-2010/8:20:17-7:00
Boron is an open source interpreter based on REBOL language syntax. It implements only a minimal portion of the language, but it does have working Windows and Linux binaries available for download. Hard core developers should be aware that this exists:
http://urlan.sourceforge.net/boron/
Endo — 23-Jun-2010/9:12:21-7:00
No license problem?
Nick — 23-Jun-2010/10:26:37-7:00
It's written by the same person who developed ORCA, which implements about 50% of the REBOL core language, and I think has seen some production use by the developer (I think only in open source projects). As far as I know, there have never been any legal issues.