Good Form

Good form is essential to the safety and efficacy of your workout! By not doing a full range of motion push up, pull up, squat, etc. you are training your body to only be strong through a partial range of motion. Yes, you will probably be able to complete more reps or use a heavier weight if you cheat on the range but have you really done yourself any favors? What if life requires you to do something that requires strength at the bottom of the squat for example? What if you need to pull yourself up from a dead hang? If you haven't been fully extending your arms on pull ups you will not have the strength to pull yourself up! If you haven't trained it, the strength will not be there.
A couple of good articles. The first speaks to good form. The second is a crossfit journal article on the foundations of CrossFit.
http://www.stumptuous.com/cms/displayarticle.php?aid=39
http://www.crossfit.com/journal/library/Foundations.pdf

Workout:
3 6-packs (it sounds like a good idea when you start...thanks Will for naming this one!)

6 rounds
6 Burpees
6 Man-makers
6 Turkish Get ups

In case you don't know what a man-maker is: Get a pair of DB's. Keep a hold of them and put them on the floor and jump back to plank, row each one, do a push up. Jump back to standing, clean the DB's, jerk the DB's and 2 two overhead walking lunges. That is one man-maker.

Oh....and make sure your form is good!