I'm getting tempted to trying to run Kubuntu. Does the clean image from this script work?
Would be very nice. And the other thing you need is the low-fat package, am I right?
I imagine that it would run a little bit better considering Unity is mostly made for a large array of shortcuts that include the Super key, unless you reconfigure. It would however be a good foundation to work out of. KDE installs KDM, and from there you can naturally start Unity.
Reminds me... Does Gnome Shell work with armhf?
That would be really nice to try out, considering it's a lot lighter, at least from what I've seen.

EDIT: Gnome Shell is available
Will try to install it on rev54 with the kernel I know kind of works. (2.6.35)