You have probably noticed, that Ruby 2.3 was released during Christmas
so we can move forward with the change proposal  and get Ruby 2.3 for
F24. Actually, I already obtained build target for Ruby 2.3  and
build ruby-2.3 package and now its time for you to help :)
What does it means? This is the list of packages which very likely needs
to be rebuild:
$ dnf repoquery --disablerepo=* --enablerepo=rawhide
--enablerepo=rawhide-source --arch=src --whatrequires 'ruby-devel' |
sort | uniq
You can take the and just fire rebuild, but please, you should be using
f24-ruby build target, i.e. the build command should look like:
$ fedpkg build --target f24-ruby
If you forget to specify the target, you'll do build against Ruby 2.2,
which is not what you want.
If you don't make it soon enough, I'll very likely rebuild your package
sooner or later. I'll be using fermig  to do that as I did during
previous rebuilds. If you don't like me to touch you package for
whatever reason, please let me know (Mamoru, I suppose you are going to
rebuild your packages yourself, right?).
You can follow the progress at:
$ koji list-tagged f24-ruby
As always, any help/testing/feedback is welcome.