I think it was compiletc which someone had mentioned might be a little flakey if added to a persistent /usr/local.
Maybe it was the X dev package?
In any case, I'm wondering if it's safe to add these packages to local...maybe I'm just being overly cautious. I have most of the other dev packages already in local, but when I compile I reboot into a clean system + the devs. Is this recomended, or am I okay just extracting what I need into local so I can compile whatever I want whenever I want without rebooting?