Richard Eisenberg
I'm oddly drawn to the idea of a turtle -- except that turtles are slow. But animals are cute. Maybe something involving a fox, given that foxes can be clever? Octopuses are also known to be very clever, but maybe GitHub has octopuses covered.
In general I'm rather neutral on the logo question. There is a fine line between "juvenile" (which may detract from the project's credibility in the eyes of some) and "cute" (which I think is universally a Good Thing); the current rather boring logo was a quick attempt to satisfy the need for some logo while recognizing that I lack the artistic ability to walk that line. I don't think it's a bad logo but it's quite dull and far from being a *good* logo. I do hope someone steps up to do better. Logos aside, I do feel the need to correct the record here: you clearly have not seen how quickly a turtle can move when offered banana or shrimp. They can be quite quick when suitably incentivized! Cheers, - Ben