Joyce emulates the Amstrad PCW on Unix, Windows and Mac OS X. Since it's written using SDL, it shouldn't be too hard to port it to other platforms such as MacOS Classic or BeOS.
Joyce v2.2.9 Changelog:
http://www.seasip.info/Unix/Joyce/index.html
Joyce v2.2.9 Changelog:
This adds emulation of the Electric Studio light pen.
http://www.seasip.info/Unix/Joyce/index.html