That...thing...doesn't really do much for me as far as a corporate logo goes. Rather complex shape (see references to scaling problems), sorta catish but not, WTH is that weird tail (cat, four legs and a...), this post is the first reference to "octo" I've seen in the months I've used the service, there's 5 limbs not 8, etc. Makes me think of a little kid in a Halloween costume.
"Github" name works fine. "Git" spoofs "get" a la archiving, "hub" is central connector/repository, concatenated the name just rolls off the tongue and instantly works as a coined term. Rendered in a nice unique font, great. But then there's that creature...