OpenHatch was mentioned previously, but I'll mention it again for completeness sake. I'm now getting a "500 Internal Server Error from it." (Slashdot effect). Also, there's a list of projects with mentors on the "Teaching Open Source" wiki. Furthermore, as people noted, most open source projects could use some help and you can approach those that interest you.
Finally, touting my own horn, I'd like to note that I'm willing to mentor people with their first steps in my own open source projects. Hack on!
I'm glad to see an apology for Turing's treatment being set straight. Alan Turing definitely didn't deserve the bad treatment that was inflicted upon him for his sexual orientation. He certainly deserves this apology.
One historical note is that several models of computers (or actual computers) preceded the more formal computer science, but naturally, the theoretical work of Turing (and related early CS pioneers such as Alonzo Church), and their rigour should also be highly regarded.
A company is known by the men it keeps.