Current version of zthread library is 2.2.10. Current ebuild is 1.5.3. Please find attached a updated ebuild, which is nothing other than a copy of the old with the name changed.
Created attachment 7223 [details] Updated zthreads ebuild
added to portage, thanks http://cvs.gentoo.org/cgi-bin/viewcvs.cgi/gentoo-x86/dev-libs/zthread/zthread-2.2.10.ebuild?rev=1.1&content-type=text/vnd.viewcvs-markup