On April Fools Day, the Human-Murrine theme disappeared (Bug #210419). It has been reinstated. Yay! While looking for it on GNOME Look, I came across Murrine Human (note the reversal of the name), which is also a pretty nice theme. It comes in a dark human (charcoal instead of silver, but still with brown accents) variation and has blue and green versions in case you don't like brown. I'd still like a copy of the Human Murrine that had brushed metal menubars at the beginning of March, if anyone has a copy.
I've also just noticed that a new background was added and the "old" default was changed. Some have said that the heron in the default wallpaper looks like it's bleeding. I don't really think it does. I just saw it as an abstract blend of the colors in the Ubuntu logo used to make the shape of a heron with no real meaning to where each color appeared. I guess enough people called it morbid that a change seemed to be in order. The current version of the heron wallpaper does not have red all up and down where the neck is. It's just at the base of the neck, like a necklace of sorts. There's also now a version of the wallpaper included which does not have the heron at all—just the artsy brown background with a loopy, swirly texture.
EDIT: Just spotted this blog as a referrer to my page (yay stats). Troy Sobotka has written about how the wallpaper was changed and gutted of all its pretty colorful flare. Taking a look at the images he posted, it seems more has changed than I initially noticed. The background behind the heron is now all brown. The colorful swirls are gone, replaced with a few lighter-brown swirls. He has links to the current version and to his last remix of the colorful one. The one I liked with the tall bird that so many people claimed was bleeding can be found here (SVG). So I guess the answer to "why is Ubuntu brown and ugly?" (hey, it gets asked a lot—the colorful wallpaper was a step away from that) is "well half-way through development it was really pretty, and then...it stopped."