We're having a big debate in the office between the designers and developers about the role of the PSD in generating a site. My feeling is that, for sites of a certain scale, you should develop the typographic rules, and perhaps even the layout, in HTML/CSS rather than Photoshop. As with any medium there are subtle differences in execution.
When adhering to visuals - it is sometimes the case that the designer will impose unique rules readding, colour etc per each page. A link on one page may have a bullet point, on the next it doesn't.
Conversely, if you begin your design in CSS/HTML, impose an information hierarchy starting with type, then layout, and finally graphics (which is where the PSD comes in) you will be more likely to create layouts that reflect the content hierarchy consistently - and incur less overhead trying to achieve an arbitrary quest for pixel perfection.
This article goes into greater detail about the whole concept of skipping Photoshop in the initial design phase.
“The text in Photoshop is not the text on the web. Once you’re looking at a static Photoshop mockup you can’t quickly change the text without going back into Photoshop, changing the text, saving the file, exporting it as a gif/png/jpg, etc. You can’t post it online and tell someone to “reload in 5 seconds” like you can when you quickly edit HTML. You have to say “Give me a few minutes…”. Also, type in Photoshop never seems to be the right size as type in HTML. It just never seems to feel the same. It doesn’t wrap the same, it doesn’t space out the same.”
Why we skip Photoshop
As a caveat, I think this argument is less relevant to smaller, brochure style sites, but holds true for CMS/e-commerce and heavily data driven sites - i.e: The Guardian or the Times sites.
What do you guys think?