Thanks Simos.
I gave the 7za command line tool a try, and it seems to work quite well, and handily solves
the cross-platform unicode filenames problem. (it either correctly figured out that my ext3
filenames were utf-8 based on the locale, or else it just hard assumed utf-8 period. I'm fine
with either case, didnt review the source to see which it was... )
I suppose the answer then is to steer clear of the most popular archive formats when
you want to release an archive containing unicode filenames to a multi-platform audience.
Alternatives, such as 7zip appear to work quite correctly.
I found this on wikipedia:
http://en.wikipedia.org/wiki/Comparison_of_file_archivers
So we have a handful of valid choices after all.