I just noticed that my ruby1.9 build of August 17th includes a Fiber 
class.  The implementation shares the file cont.c with Continuations, 
but it is still undocumented and I can't figure it out.

Can anyone (Sasada-san?, Matz?) explain Fiber?  How likely is this to 
remain in the final version?  And what about these new external iterator 
  methods that have appeared in Enumerator?

These are exciting times!

	David