I've started and stopped on this idea (mine has always been something along the lines of "Fireworks on the web... but better") several times over the past couple of years.
But I've always left it on the burner because, as technology stands today, it'd have to be an installed application. Importing a bitmap and deleting its background pixels, complicated vector drawings, etc. etc. would be impossible (or so damned difficult/manpower intensive as to make them near impossible) to build in today's browsers. And for me to be interested in sinking several years of my life into it, it'd have to be a webapp.
So, I just end up waiting for someone smarter/ballsier than I to do it. And waiting...
Me too, pretty much. Although I've not even dared to think about uploading/editing images.
My vision is something where you can create and use templates for stuff like header, menu, columns, footer, implement styles for fonts, edit styles such as gradients, shadows, corners.
Interface should be something like hovering to see which elements are affected by the current rule, and then picking attributes and changing them.
Basically a WYSIWYM for CSS3.
I am certain something like this will appear this year.
You've got a spec from Jason Santa Maria - is anyone going to go create? :)