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Perhaps not so much a Serious UI Toolkit(TM), but anything that eventually compiles down to GL would work too. This is how play-clj does it: binding to libgdx, which eventually calls some OpenGL methods.

While I did jokingly say "Serious UI Toolkit", there's more than a few awesome applications on Android that have very, very simple UI widget requirements. Particularly games, which according to the article, they're focusing on.

JUCE also does.

http://www.juce.com/

Kivy does too.

http://kivy.org/