Peldi at Balsamiq has a great blog. His post on Jason Fried’s talk really echoes my sentiments. Particularly:

One thing that they do differently from me is to jump straight into HTML+CSS for their Mockups. I still think that’s too time-consuming compared to using Mockups to flesh out your UI ideas. I do agree that you don’t really need more than a mockup, or a set of mockups, as a spec.

I think this is particularly true where development is outsourced. People contracting their development quite often don’t have the resources to dive straight into coding the HTML interface, and may need help to describe what they need with sufficient clarity. I’m a big fan of using prototyping tools to present visual specs to developers - still working out a consistent methodology for this. Stay tuned, I’ll have more on this.