Google did the terabyte slightly slower (68 seconds) on 4x fewer machines, but did the petabyte in 6 hours and 2 minutes (around 1/3 of the time of Hadoop) on nearly the same number of machines (4000).
You don't have to sort a terabyte in 62 seconds, you could do it on 10 machines and it would probably take you less than a day.
If you are a company that needs to sort a petabyte once in a while and your data resides on the Amazon cloud, you could get 3600 high-cpu EC2 instances and do it for about $12k.
A petabyte is on the order of 100k bytes for every person on the planet. If you have that much data that you need to sort in less than a day, you can afford it.
I'd actually be curious to see what would happen if you tried to sort a petabyte with 3800 EC2 nodes. I wonder how much worse your performance would be? EC2 instance-local storage is pretty slow by default (the "first-write" problem), but if you used multiple EBS volumes on each node you might be able to get pretty good I/O performance.
IIRC the rules require the data to be read from disk, sorted, and written back to disk, so that's at least 32GB/s of disk I/O by my calculations. Also, the cluster has fairly weak bisection bandwidth.
