WebProNews has an interesting discussion regarding Rick Skrentas purchase and potential move of Topix.net to Topix.com. Rich is concerned that the move will impact his Google traffic, and given that it's such a big website and search is critical to him these are perfectly reasonable concerns, internally we call it "Search Traffic Continuity Planning" and it's likely he'll see more than a couple of weeks disruption even if he does 301 the domains. This is especially interesting because Topix.net serves Google Adsense ads, so any hit in their traffic has a direct hit on Googles revenue.

What we have asked for previously is that Google add in a feature to Webmaster Central whereby website owners can specify additional domains mapped to an IP or similar that should be treated the same as the primary, these could then be interchangeable so that the owner could select the one they wanted to be displayed in results without impacting their website - much like Google already does with canonical domains.

This probably means abstracting the domain and additional canonical domains out of the processes in Googles index and algorithms - no mean feat I'm sure.  However it would be very useful and provide much more flexibility for website owners in these circumstances. Vanessa please see what you can do in Webmaster Central, it would be a big move forward in the search traffic continuity process.