There was a follow up post on Blogstorm. This post actually looked at the detail at the new URL structure and summarised that we (the SEO fraternity) might get some brand new data our PPC colleagues are all too used to.
Patrik Altoft suggests that
Perhaps the cd=7 (click detail = 7th?) is the ranking and ct=res (click through = results?) is indicating that the click came from organic search rather than a universal search (news or video) result.
Matt Cutts chimes in later on in a comment to this post.
I think if you do experiments, you’ll be able to confirm your speculation, Patrick and Brent Nau. As Jamie mentions, I think this is awesome for webmasters–even more information than you could glean from the previous referrer string.
So, watch this space !