There was a fantastic resource about Multiplayer Level design from David "DavidM" Munnich. Although done in Unreal Tournament context it was really informative.
I don't know if it's still available (could not find it), taking into consideration it was hosted at the defunct planetunreal I doubt it survived.
That's the one I was thinking of too, but also, how relevant is that still today? "Levels" in various categories of video games have evolved far beyond the fairly basic arenas of the UT / Quake era.
In terms of geometry density (detail) they have definitely improved by many orders of magnitude but in terms of layout I think most games have actually gone backwards with vastly simple levels to navigate. That (exagerated) meme about level design in 2010 is still fairly relevant [1].
