Someone told me that chocolate doesn't have caffeine in it, it has a different chemical that has similar properties. He heard it from a college chemistry teacher. Can anybody confirm/refute this?

indeed it does not contain caffeine:

Pharmacologically active ingredients of chocolate
Compound Amount
(%W/W)
Neurotransmitters:
Serotonin 0.62 - 5.82
Histamine 0.04 - 0.13
Methylxanthines:
Theobromine <1.3
Caffeine ND
Tetrahydroisoquinolines:
Salsolinol High
Methyltetrahydroisoquinoline <0.01
Amines:
Phenylethylamine 0.02 - 2.20
Tele-methylhistamine 0.01 - 1.54
Spermidine 0.05 - 1.15
p-tyramine 0.02 - 0.35
3-methyloxytyramine 0.02 - 0.33
Tryptamine 0.03 - 0.18
Spermine 0.00 - 0.13
ND = not detected
Source: Biochemist, Apr/May 1993, p

The Science of Chocolate (http://www.exploratorium.edu/exploring/exploring_chocolate/index.html)

http://www.howstuffworks.com/chocolate.htm