Aarrgh, Eli. You've made me obsess about rhubarb now. I already left two comments on Eli's post, and I feel ridiculous posting a 3rd comment, so here's my own post.
Eli, I think one solution to rhubarb soupiness may have to do with the way it's cooked. (Another solution of course is pectin or gelatin.) Christopher Kimball suggests sauteeing rhubarb before including it in pie, and here's someone else--the Wednesday Chef--who has a roasted rhubarb recipe. And as you can see in the picture, her rhubarb retained it's shape and didn't go all gooey on her. Of course you'd need some gooey-ness in preserves, but perhaps you could mix the two to get the right consistency?