This IS a right or wrong question. (I know I'll get modded down, but I guess I had to say it)
To maintain a binary package system for gentoo is just against its philosophy. The spirit of gentoo is its ports system, with allowed the gentoo system to be extremely portable and managable. To maintain such a binary package system for gentoo is almost like saying you want to maintain a giant insecure software repository for OpenBSD...
After all, isn't it the built from source concept that makes gentoo different?
Actually, it REALLY isn't that difficult to make it easy to maintain a set of binaries for gentoo. A simple method is to adopt e.g. rpm/dpkg for use in gentoo.
In general, though, if you have to ask (how), packaging would be very difficult you, let alone managing or adopting a binary packaging system.