I'm not sure that you can say definitively that some roles are better filled by consultants, but I would say that some projects are better handled by consultants.

Ajax is an important development for Web applications, and its importance is only going to grow.

Problems with visual design can turn users off so quickly that they never discover all the smart choices you made with navigation or interaction design.

Building technical systems involves a lot of hard work and specialized knowledge: languages and protocols, coding and debugging, testing and refactoring.

Google is making a huge investment in developing the Ajax approach.

Ajax isn't a technology. It's really several technologies, each flourishing in its own right, coming together in powerful new ways.

The more everybody knows about all aspects of the problems we face, the better off all of us will be. Less time spent explaining things means more time for coming up with creative solutions.