${S} already defaults to ${WORKDIR}/${P}
this version isn't even in portage.
Oops. I looked at the CVS (http://www.gentoo.org/cgi-bin/viewcvs.cgi/*checkout*/net-analyzer/ethereal/ethereal-0.9.16-r1.ebuild?rev=1.6&content-type=text/plain) rather than at the productive portage tree.