The current gaim 0.80 ebuild specifies a dependency on gaim-encryption-2.27 if the crypt use flag is set. When I built this gaim, the plugin was missing from the list (and according to the gaim-encryption people, gaim-0.80 requires 2.28... Anyway, simply changing the number in the depend worked here.
Fixed. Thanks. I had actually patched 2.27-r1 to work, but still forgot to bump the number in gaim.