Forum OpenACS Q&A: Re: Re: Continuations for web programming?
Some (most?) of the people espousing web continuations definitely seem to be trying to do richer more GUI-like web UI, or trying to make the same code work identically both on the web and on the desktop. So that does seem to line up with Don's, "probably a bigger win for desktop GUI apps" thesis.
On the "are the web GUIs your write complex enough to worry about" question, well, I personally have been spending only small percentages of my programming time on web work of any sort (much less complicated web UIs) for a few years now, so I'm clearly the wrong person to answer that question. But I'm definitely interested in what others think about it, as in Don's posts above. :)