To be fair, it came as an asset in an unrelated acquisition (On2). But it just sat their (pointing to this Duck Corporation history page) for a long time.
I first inquired about it on 11/4/09. After several attempts, I got back a response "from management" on 3/25/10 that they didn't want to sell it. Understandable.
Now http://www.on2.com/ points to a Google explanation page about the On2 acquisition, yet http://duck.com/ points directly to Google search.
Google closed its acquisition of On2 this year. On2 was known as The Duck Corporation as early as 1995. That's why duck.com belonged on On2--duck.com was registered more than a decade before duckduckgo.com, and I have to admit when I see duck.com, I still think primarily of the Duck codec.
It looks like duck.com changed nameservers from ns1.on2.com to ns1.google.com about a month ago; my guess is that duck.com started pointing to Google as part of the switchover of nameservers from On2 to Google.
I don't know what Google's policy on selling domains is. I don't remember Google ever sell any domains offhand, but I dropped an email to one of our domain people to ask about that.
Considering how many acquisitions Google has made, and that "organize the world‘s information" is part of their mission statement, I'm dismayed they think deliberate linkrot is an appropriate way to handle acquired assets. It's not as if they have no capacity to keep those pages in the web.
I first inquired about it on 11/4/09. After several attempts, I got back a response "from management" on 3/25/10 that they didn't want to sell it. Understandable.
Now http://www.on2.com/ points to a Google explanation page about the On2 acquisition, yet http://duck.com/ points directly to Google search.