A post-hoc analysis by Coffman et al (2007) examines some of the questions I raised in my initial post about Behavioral Activation. It is clear that the apparent superiority of BA is due to a sub-group of severely depressed and chronically depressed individuals. For these individuals CT had virtually no benefit while BA had some benefit (but they were still clinically depressed).
I recommend taking a look at Coffman et al's study for a discussion of the characteristics of this sub-group, they go into quite a bit of detail. I'll think it over as i have time and hopefully post more about it in the near future.
Coffman, S. R., Martell, C. R., Dimidjian, S., Gallop, R. & Hollon, S. D. (2007). Extreme nonresponse in cognitive therapy: Can behavioral activation succeed where cognitive therapy fails? Journal of Consulting and Clinical Psychology, 75, 531-541.