I had been using Disqus as my comment provider since I redesigned my site.  I really like having threaded comments, but I decided to ditch them, for two reasons.

• They store all the comments in their database, and generate the display in my pages on the fly.  That means that comments ultimately live on their servers, which means if they ever go down, or something happens to the Javascript in a visitor's browser, my comments go down.  It also means Google can't index comments.
• I can't see a good business model for them.  This is made more troubling because of #1.  If they ever croak I anticipate nothing more than an email saying "We're sorry but Disqus is no longer able to serve your comments it's been a pleasure serving you have a nice life"  As nice as they might be, making sure my comments are preserved will be the least of their worries at that point.

Like I said I really enjoy the output of the service, but with the current economic environment I just can't put myself in the position of relying on a company with no real revenue model that I can comprehend.  I don't think this is just Disqus, either.  I would like to use Seesmic video comments too--but again, if they ever go out of business (and they just laid off a handful of people) then I would assume that all the content they host goes to Web 2.0 heaven with them.

Nothing against the service or the company, as I said I've been happy with the results.  But I suspect you will be seeing a lot more people hesitant to rely on 3rd parties to host their content as the Depression unfolds.  This really all goes back to what I've been calling the SaaS trust issue--how much can you really trust your critical service providers, and how much will it cost if you get that bit wrong?