Another way to do something along these lines is have a "fat binary"
that is equivilent to "isaexec" on Solaris, and then one can just
exec the "right thing".
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/cmd/
isaexec/
http://docs.sun.com/app/docs/doc/816-5168/isaexec-3c?a=view
Doing something like this doesn't avoid the fat binary support needed
to make the initial isaexec command run, but you could then support
about as many architectures as you wanted to out of the same set
of filesystems.