This reminds me of a problem I've pondered for a long time now, without coming up with an answer. Why are web pages designed with Photoshop in the first place?
Photoshop was never meant to be used for web design, any more than Visio was meant to make wireframes. It's simply the best tool available for the job, and requires a lot of workarounds and good behavior on the part of the designer.
Spending days or even weeks designing Photoshop comps that then have to be cut up, converted, and manually translated into suitable graphics for coders to work with is inefficient, and often leads to final products that don't match the designer's work. Text is the most obvious example, but I'm sure anyone can think of myriad places where this happens.
Is there a tool that lets designers think about the structure coders will have to build WHILE they're designing the screens? I'm not talking about a WYSIWYG code generator—those have been tried over and over again, and they all suck. I'm talking about a tool that lets designers design, lets coders code, but helps the designer think about what the coder will have to do with the graphics, including keeping text as text, identifying UI elements that need to be reused, seeing how layouts will look when the browser resizes, etc.
If this tool doesn't exist, it sure would be a great project for someone to build.