The first question I received (and indeed the first one I asked a few weeks ago) regarding the Yocto Project was, “Yet another Linux distribution?” We certainly have plenty of those, adding one more would really only serve to further fragment the embedded space.
So no, Yocto is not a distribution (like Fedora and Ubuntu) and it is not a platform (like MeeGo and Android). The Yocto Project is a workgroup (as described in the Linux Foundation Announcement) and the core bit of software behind it is the Poky build system which has its roots in OpenEmbedded. So, the Yocto Project is targeted at making it easier to create your own Linux distribution. It also serves as an umbrella project to collect things like BSPs all in one place.
The ultimate goal is to provide a common collaboration point from which we can reduce the chaos in this space and make it easier for people to bring Linux based devices to market.