GIMP 2.3.17 is a snapshot of current development towards GIMP 2.4. The source code can be downloaded from the usual places. Check the NEWS file for an overview of the changes in this release.
Unfortunately a rather bad bug has sneaked into this release. We encourage you to give it a try nevertheless, but you should expect frequent crashes. The 2.3.18 release will follow soon.
http://www.gimp.org/