Thought I'd give it a stab. My main design goal was to emphasize the card art. There were a couple reasons. First, we got some really awesome art and I thought we should try to showcase it. And second, after about a month of playing, the only thing you look at when a card is played is the art. You already know everything else pretty much. So I tried to take the most important part of a card and emphasize it.
To that end I got rid of all the extraneous borders. The top bar is semi-transparent to let more art through. It's black for unupped cards and white for upped cards. This is another quick and more obvious visual cue that the card is upped besides the name change and the title text color change in the current cards.
I think the text description area is a tad bigger than the current one. A nice gentle gradient for the text area and the element's mark in the background helps tie all of an element's cards together.
Edit:
I changed the font from the sans serif font (Arial/Helvetica/Gills Sans or whatever it is) to Fontin. It's a good font for small sizes and it is not too drastic of a change since it's very sans serif-y. But I think it gives a bit more personality.
Here's (
http://elementscommunity.org/forum/index.php/topic,20899.new.html#new) the link to the Card Art section.