Does Google use WHOIS data?

[born2drv]

I've heard a lot of people mentioning Google uses the Whois data to compare sites, identify sites hosted on the same server, etc.

Is this true? And if so, why don't they use the WHOIS data for regional filtering instead of IPs?

[rfgdxm1]

The only thing that is known is that Google uses this to know if domains were allowed to expire.