1.9 onwards (planned) runtime changes

Hi,

as I could not find any reference in recent postings, please allow for
this
question:

is there any web site that lists planned and current changes in the C
Ruby
runtime for Ruby 1.9 and onwards?

I’m especially interested in threading support, but also in other
changes
that might significantly influence the behavior of ruby programs, but
are
not directly reflected in the core API documentation.

I know that programs are supposed to be largely runtime agnostic, but
some
limits and possibilities of the runtime might still influence the way
certain features can or should be used.

Thanks
Rainer Frey