Whitey - 12:30 am on May 31, 2010 (gmt 0)
That's an interesting thought. Since this is algorthimic , it would be reasonable to assume Google has been collecting data , perhaps , as you say , on a category basis. Some sort of data matching validation - site to a category database match.
I think i've been noticing this type of validation with mis spellings over the last 12 months or so, which all though different in it's application , provides for a similar concept of execution.
It's all highly speculative and imaginative , but it does make potential sense.