How Expensive is it to Run Facebook?

I posted earlier about Facebook's eye-popping growth - 600,000 new users per day. What exactly does that mean? Well let's try to figure it out. If Facebook allocates 50 MB of disk space for each new user, that's 30 million Megabytes, 30,000 Gigabytes, or 30 Terabytes - PER DAY. Even if we assume 5 MB per user, that's still 3 Terabytes per day - that's almost 1,100 Terabytes per year. Now add in memory, power, CPUs, UPSs, etc. That's quite a data center!