After a long period of development on the 1.5.3 requiring snapshots, an official 1.6.0 release now incorporates all the fixes made during that time.
Apparently they had a 1.5.3 release last January, too.
So I'm missing any mention of "ulog" and the reliance on the "legacy" mongo-c-driver continues.
Ebuild in tree.
rabbitmq is mentioned, though.