This issue comes up a few times a year (isn't it in a FAQ somewhere?) Anyway, take a look at these threads:
Yeah, this is one of the most persistant 'Wine dream' around :-)
I had once a long discussion with a fellow hacker on this subject (going into the likes of using Valgrind's virtualization engine to output non-X86 code to do dynamic translation and so on). We agreed that before starting with Wine, one could start with running, for example, Linux/x86 binaries on Linux/PPC. That would already validate the fact that you can draw the line at one point and from there run such an heterogenous environment.
It's a very nice subject... A pitty it has such a low importance (seeing how X86 dominates the desktop market).
Lionel