Last month Matt Cutts mentioned that there was a new datacenter Google was testing, however he didn't get into too many details about what it was or why they were testing it.
Today, Matt unveiled 'BigDaddy' (the name they gave it) in his blog. In it he explains what BigDaddy is and isn't.
For one thing, BigDaddy ISN'T a new algorithm. But it is a new foundation for Google. In other words, this new datacenter contains new code that will be rolled out to the other datacenters in the coming months to help improve Google.
While some are reporting that they are seeing different results on the datacenter Matt insists that is more a case of the changing infrastructure than an actual algorithm shift which we normally associate with a Google update.