According to the blog post that introduced the new design, the reason behind creating a visual representation of the repository was for identification. For a developer, often they will be working on a few different repos at once, not just one. The idea is that each repo will have a basic "signature" in the color across the top. After enough time spent on the project page, the developer will just be able to distinguish the project from one another just by the color bar.
Hey Smokey, I was searching through HN posts and I saw that you went to Iowa State. If you don't mind, can I ask you a few questions? Probably by email.
Hmm, that's interesting. The first example doesn't seem to work. I just get "#<unknown 0x00000007>". I wonder if it has to do with a difference with gcc.