In [ruby-talk:13049], matz / zetabits.com (Yukihiro Matsumoto) said:
>   * add configure option to enable native-thread (which is off by
>     default). 

I'm no thread expert either, but to this I would like to add that, even when 
enabled via configure, perhaps native thread support should be a runtime 
option.  This way, if I really would rather use "green" threads in some 
specific case, I can do it without having to keep multiple ruby binaries 
around.  This will also help with ensuring that my scripts will work on 
systems lacking native thread support if it ends up that there are subtle 
differences between the two.  It may even help with debugging native thread 
support...

Henry.