I've been following Couchdb's progress on and off for a bit now, and finally shaved enough corners off my pile of square tuits to actually fiddle with it. Setup an instance, got it running, made an ebuild for the current stable, etc. Very cool, and I was about to start coding a blog-type-thing (for here actually) in ruby. And then I read that not only was the XML output going to be changed to JSON (far saner), but that the entire query language was going away. Didn't make much sense to code to a dead interface, so I let the code REST (get it?).
If, and this is a big if, clustering and mapreducing come together in the obvious (but decidedly nontrivial) way, I really will wet myself.