I could always see why 37signals can skip Photoshop as part of the design process, but I’m starting to believe that more and more product-driven companies can too. Comps build up expectations and the final product will never satisfy everyone. Jason makes a lot of good points here, but this one especially rings true.
Photoshop is repeating yourself. Ok, so you’ve spent 3 days on a mockup in Photoshop. Now what? Now I have to make it all over again in HTML/CSS. Wasted time. Just build it in HTML/CSS and spend that extra time iterating, not rebuilding. If you’re not fast enough in HTML/CSS, then spend the time learning how to create in HTML/CSS faster. It’s time well spent.