It looks as though at this point in the world of Ajax we don't really have great solutions for "accessible Ajax". Dennis had a good presentation showing some things we can do now on the accessible Ajax front. But at this point, as they say: " some problems don't have solutions, they can only be managed".
During the Q&A. Someone in the audience brought up WCAG 1 vs WCAG 2 in relation to separation of behaviour/content/presentation. Particularly at issue was perhaps WCAG 2 seems to be making allowances for blurring the lines.