David,

I'm a fan of agile myself-- that being the method I've been working under for the last few years. I wouldn't say that the primary theme of the work is that implementors should frequently say no-- but I would hope that it underlines the need for frequent, communication.

As someone noted above, and I think it is a valid criticism, the best design method in the world doesn't work if the customer cannot (or will not) articulate a solid specification.

Thanks for reading, I've enjoyed all the different perspectives,

Brad