I agree though, that DDG is a blip -- a teeny tiny blip in the search engine market -- so, quite frankly, I'm not sure why they care so much, or at all.
I think the difference in engagement by those guys is that Cuil was trying to be stealth and downplay the hype of being "google 2.0 by ex-googlers" whereas your marketing has been squarely aimed at them.
Intentions aside, Cuil was presented as a "Google killer" to orders of more people than know about DDG. But higher level, I don't think DDG warrants their engagement at all. There are much bigger fish to fry, so-to-speak, and yet I don't see them on all the higher profile search engine stories out there across the Internet.