Here are some thoughts:
First one to hit Hamming distance of 5.
Lowest average Hamming distance over top n trials.
Most trials in x hours.
...
First one to hit Hamming distance of 5.
Lowest average Hamming distance over top n trials.
Most trials in x hours.
...
Having said that, I'm betting that the EY people chose this particular problem since highly-optimized algorithms are easily available to all - meaning that the amount of HW one can throw at the problem (and luck) will likely be the determining factor in who wins.
Which HW should someone use? Well, EY has a cloud computing program, and it's right there....
That is, I think, the point of this contest. Make a problem that's hardware-intensive, so that people will try deploying it on the EY cloud platform and get them into the proverbial front door of the product family. They're not interested in novel algorithms; they're interested in getting people onto their platform, and getting them used to it.
It seems that their goal (by having defined a specific dictionary) was to have lots of people tweeting those dictionary words to @engineyard.... sort of a way to get better twitter-driven pagerank.
I originally though this - http://www.engineyard.com/private-cloud - was a cloud environment a la EC2 based on the title (which would work with my theory), but reading more about it makes it seem like it's still optimized for Rails, and hence not for this.