According to the recent interviews with Yoshi-P, they're thinking of using Flash for community-built UI addons.

As someone who'd probably wind up getting into building addons if they were in something like Lua or Ruby, I'm slightly frownyface at the idea of using Flash, but I'm willing to consider that's out of ignorance on my part - I've never deeply worked with Flash before, so I am possibly making a snap aesthetic judgement. I am aware of several problems with its use, but...

Is there anyone more knowledgeable about UI scripting who could chime in here? Alternately, potential UI addon creators, what languages are you most comfortable with and would prefer to use?