Penne is just the particular shape of the noodle, a tube with the ends cut on the diagonal. Penne is Italian for quills, sometimes it is called Penne Rigate, that is for the shape with ridges along it, to help hold pasta sauces particularly thinner tomato ones.
My favourite name for a shape of pasta is orichiette (little ears!)
Kyles - I love orichiette too!!! I have a casserole I use them in - if I haven't posted it I will. I also like cavatapi (sp??) - will post that recipe too. I'll probably post these tomorrow - I'm enjoying a nice, relaxing Sunday evening 8) and I'm afraid thinking will hurt!
coquille - if you put the term rigate after ANY shaped pasta it means it has the lines, or ridges in it - specifically rigate means striped. Now, it's just a matter of remembering the term "rigate" LOL.