And, a possible security vulnerability on WEBrick of old versions of ruby is reported.
ruby-1.9.1-p430 and ruby-1.8.7-p302 are released to fix it.
You can get binaries of them from "Release", too.
ruby-1.9.2-rc1 has released, too.
1.9.2 is scheduled to become the next stable version. This is the releace candidate of it.
You can get binaries from "Developping versions snapshots".
ruby-1.8.6-p388 is also released, but it has a build problem with mswin32.
So its binaries is not available now.