Hi, thanks a lot for including syncevolution into portage. The only thing missing is that the syncevo-http-server binary needs the twisted.internet package provided by dev-python/twisted. The HOWTO page mentioned in this report even lists twisted-web as a dependency. Installing twisted-web made the syncevo-http-server run, because it has twisted as a dependency, but I don't know if it is not too much.
Fixed in 1.1.1 ebuild