What does the MHz of RAM really mean?
Yes, it's the maximum number of clock cycles per second that the RAM operates on. With Double Data Rate (DDR) RAM, it actually communicates twice per cycle. So for DDR:
200 MHz clock rate × 2 (for DDR, 1 for SDR) × 8 Bytes = 3,200 MB/s bandwidth
This is why chips are now named for their bandwidth, not their frequency alone. Above chip module is called PC-3200, not 200 Mhz. It's still necessary to know the clock rate, to ensure that the motherboard/CPU can operate at that clock.
See the Wikipedia article on DDR SDRAM for more information.