There's a 10 May 2010 net-dns/bind changelog entry recording a small change to all bind ebuilds. named.ca was renamed to named.cache as fetched from upstream, as the .ca version apparently no longer exists. Unfortunately, the shipped config file wasn't patched to match, so it still tries to load named.ca upon service start. Naturally, it fails to find named.ca and thus fails to start. I just installed bind-9.6.1_p3-r1 and confirmed the change in filename without a corresponding change in the config file, in the binpkg (FEATURES=buildpkg), but the change was apparently made to all current ebuilds. I checked both bugs and packages.g.o to see if it had been caught since I synced yesterday, but turned up nothing, so here's the filing. I don't see how emerge info would help here as this one appears pretty cut and dried, but if it's needed for some reason, just ask. ~amd64 no-multilib, FWIW.
Sorry guys %) But its already fixed now so I'll close this bug. Re-sync and try again, if there are still issues feel free to reopen this bug.