mcglynn - 2:50 pm on Jun 20, 2011 (gmt 0)
I have a handful of domains formerly owned by widget manufacturers, bought for the purpose of 301-redirecting into a hierarchy of widget information pages on my main site. The WHOIS info and registrar are different (e.g. the main site is a private registration at registrar A, and the 301'd sites are registered at registrar B with slightly different data). It is my understanding that Google can read private registration data (they're a registrar too, no?) so it is possible they've normalized both addresses and decided them to be equivalent.
The sites use different IP addresses, but within the same class C network.
Doing a google search for the FQDN of one of the 301'd domains, e.g. turbocharged-widgets.org, indeed shows that domain at #1, with the title and snippet of the page that users would be redirected to.
Curiously, if I search for the name without the TLD ('turbocharged-widgets'), my pages still rank highly but show the proper canonical URL and domain. IOW it is only when I search for the actual old domain, with the .com at the end, that Google rewrites the URL in the SERPs.