After a bit of fiddling with Buzz Launcher and WidgetLocker, I managed to get a customized Ubuntu Phone-esque home and lock screen combo. I'm using a stock Samsung Galaxy S II (GT-i1900) with Android 4.0.4.
There's an Ubuntu Phone homepack on Buzz's own Homepack Buzz (a community where you can upload and share your own home screen setups), but I took it a little further and customized it to my liking.
The plain text widgets are provided by Buzz Custom Widget, which is essentially an add-on for the launcher to create your own widgets. If you're using a homepack from Homepack Buzz, you'll almost certainly need this app to use their widgets. The font used on the widgets is indeed the Ubuntu font, which can be downloaded from the official site. The bars above and below the text are actually part of the background. The Lifehacker widget is from gReader.
The time/date and battery widgets are also custom Buzz widgets. The bottom shortcuts just came with the homepack. I have since customized them using Tiny White Icon Pack.
The music widget is from Apollo, the music player app from CyanogenMod that can now be downloaded for any Android device. There's also a small widget for AnkiDroid, the Android app for Anki, a great spaced repetition learning system.
Finally, the lock screen widgets use Missed It! for the call/SMS notifier in the bottom-right, and Minimalistic Text for the rest. Again, they're both using the Ubuntu font, as placed into /sdcard/Fonts. The central unlock widget is WidgetLocker's own Jelly Bean style slider.
The only other thing is the little left arrow button about a third of the way down on the right. That's Button Savior, which basically provides on-screen hardware keys - useful when using my phone over VNC. And that's about it!