...actually your use of ajax does not seem terribly extensive at all, and it certainly isn't the kind of site I had in mind. (It is a nice site, just not of the type i was referring to...)
No one doubts that you can often, with a bit of thought, "do things in a way that is search engine friendly" - but if that is the only reason that you are doing it- rather than because the application itself demands it, then you are compromising your site simply to get around an inadequacy in a search engine...
Pragmatically, that may be worth doing, but it is still more or less a "nasty hack". (That said, being forced to think "do I really need to do this on an ajax call or by writing to the DOM directly" is a jolly good discipline - but sometimes the answer is "yes". )
The point I was making is that going to a "content" model, as Cuil seems to, is something of a step backwards, because it exacerbates the problem with indexing content applied after the page has loaded - which it seems to be unable to parse. For such sites, the "popularity" model actually works better as web-surfers can analyze the content better than Cuil is apparently able to.