I built net-nttp/leafnode-1.10.8 on my amd64 and it seems works in these weeks, correctly. Please add '~amd64' KEYWORD to leafnode-1.10.*.ebuild. But leafnode-2.0.0_alpha20050215 doesn't work on my environment (I have not researched the reason in detail).
Just checked and net-nntp/leafnode-1.10.8 already has been keyworded ~amd64, by Simon Stelling on 21 Feb 2005.