With a bit of fiddling, I have gotten Pyd working on Linux using GDC 0.20.

http://pyd.dsource.org/

SVN repository:
http://svn.dsource.org/projects/pyd/trunk

Some notes:

(1) StackThreads doesn't work on GDC. Therefore, Pyd's support for
automatically wrapping opApply doesn't work on Linux. I had already
wrapped all of the uses of StackThreads in some version statements, so
it was a simple matter to tell CeleriD to just not use StackThreads when
compiling with GDC.

(2) Whenever I link an .so together using GDC, it gives me this warning:

/usr/bin/ld: warning: creating a DT_TEXTREL in object.

I have no idea what this means, and the resulting .so works fine, but
it's still ominous. Anyone have any insight?

(3) GDC doesn't support using the .ptr property of delegates as an
lvalue (and, presumably, the .funcptr property, though I haven't tried
it). Using .ptr and .funcptr as lvalues is useful when emulating
pointers to member functions (as Pyd does). I have fallen back on the
old struct/union trick for now.