I think it should say in the Apple System Profiler, under Memory overview. Mine says "PC100-222S," which would be CL2. 222 = CL2, 333 = CL3. Although I could be wrong.
that's weird...mine only says SDRAM for type and gives the size:512mb (soon to add another 512 chip)...but says nothing else...is it because i'm in 10.2?...and this information would be helpful in determining the next chip that i purchase.