Java or Objective C. Not a whole lot of code required in many cases though other than simple function calls to the OS. There's a ton of stuff built in, including a database libraries (Core Data). Are you going to write your own database for the logbook???
BTW, I'm amazed that you'd even consider writing for the Mac. I'm hopefully going to do the same type of thing at some point on the Mac, but with a lot more functionality (full flight planner a la RTFP without all the sucky parts, aircraft maintenance log type thing, etc.) but after all that work... I'm gonna sell it.
So, Scott and Terry (and others) - What would you pay for such a thing?
Jeez, with competition like that, why should I bother?
Heck, you may want to use the program to continue learning as you go through school, and then start selling it when you're out of school. You could probably even get some independent study credit for it later on!