Hey Mamoru,
Appreciate the efforts. I am also working towards Ruby 1.8.7 on Fedora, just released a SRPM/SPEC a few days ago that I was working on
http://mo.morsi.org/blog/node/318
Just fyi, we're also going to need this patch
http://redmine.ruby-lang.org/repositories/diff/ruby-187?rev=27408
To get rails 3.0.0 working against Ruby 1.8.7p149
http://redmine.ruby-lang.org/issues/show/2557
I'm currently working on bundling Rails 3 into rpms and creating a Fedora based virtual appliance w/ Ruby 1.8.7 on it, similar to the one I released w/ Ruby 1.9, to make testing software against multiple versions of Ruby on Fedora as simple as possible. After that I'm planning on setting up an automated test system to test the various Ruby packages we have in Fedora against each appliance.
Stay tuned for updtes.
-Mo