Ruby-mswin32

The first preview version of 1.9.1 -- expceted to be next stable release -- is available.
You can get i386 and x64 version of ruby-1.9.1-preview1 from "Developping versions snapspots".

Notice: Windows version of this release does not reach the quality of daily use.

New 1.8 patch releases are available. The leakages of patches of prevous releases have been corrected.
You can get ruby-1.8.6-p287 and ruby-1.8.7-p72 from "Release".

New 1.8 patch releases are available.
You can get ruby-1.8.6-p286 and ruby-1.8.7-p71 from "Release".

These releases contain the fixes of multiple vulnerabilities.
I recommend to update to these versions.

New 1.8 patch releases are available.
You can get ruby-1.8.5-p231, ruby-1.8.6-p230 and ruby-1.8.7-p22 from "Release".

And, snapshot release of 1.9.0 is available.
You can get i386 and x64 version of ruby-1.9.0-2 from "Developping versions snapspots".

These releases contain the fixes of multiple vulnerabilities.

New binary release ruby-1.8.7-p17 is available. (You can get it from "Release".)

New stable version Ruby 1.8.7 is released!
Download binary from "Release".

New binary releases ruby-1.8.6-p114 and ruby-1.8.5-p115 are available. (You can get it from "Release".)

These versions are the ones that measure against the vulnerability previously reported.
If you are using 1.9, get a patch from above link and apply it :-P