The MetaCard technology was acquired by Runtime Revolution Ltd. and is now available at the company's site, rebranded under the Revolution product name:
MetaCard Development Environment
The MetaCard integrated develpment environment (MC IDE) which was built using the MetaCard engine is now available as open source. The MC IDE includes the files mctools.mc, mchelp.mc, and mchome.mc.
While the MC IDE is open source, it requires the Revolution engine which is governed by the terms and conditions outlined in the Revolution License Agreement included in the Revolution package at the URL shown above.
A working group has been formed to maintain and enhance the MC IDE, and the most recent version can be downloaded there for free: