Marnen Laibow-Koser wrote:

> Since this is meant as an end-user productivity application for
> nontechnical users, and since I'd like the barriers to use of this app
> to be as low as possible, I have a couple of requirements:
> * Must run on Linux, Mac OS X, and Windows, preferably with a minimum of
> hassle in the build process
> * Must install with a minimum of extra dependencies -- ideally I'd like
> people to be able to download an executable, unzip it, and run it
> immediately, without needing administrator permissions
> * Should feel as much like a native app as possible -- I don't want
> users to have to deal with an alien UI

You'll have realised that there are a number of GUI packages which 
potentially meet your requirements, though none is perfect; be skeptical 
of anyone that says the particular one they're cheering is, without 
reservation, 'the best' or 'the only'.

As an alternative to single posts which tell you which GUI package that 
author happens to like, you may find this 2008 survey of around 400 ruby 
programmers specifically on GUI programming in Ruby of interest:

http://www.pressure.to/ruby_gui_survey/

I wouldn't say that being most used or most preferred is an indicator of 
which is best; lack of knowledge and inertia play a part. But you might 
assume that the most-used cross-platform GUI packages (Ruby-GNOME2, 
Shoes, wxRuby) are used for a reason, and start by evaluating some of them.

Bera in mind that Swing/Monkeybars may be disadvantaged in the poll by 
being tied to a less-used interpreter. But Swing/Monkeybars gets a good 
deal of regular promotion to compensate.

cheers
alex