Download here:
XOOPS 2.2.3 Final full package
XOOPS 2.0.13.1 or later to XOOPS 2.2.3 Final
XOOPS 2.2 or later to XOOPS 2.2.3 Final

Note that apart from the PM and Profile modules, these packages do not contain modules and instead we point to the Module Packages

Also note that if you have installed XOOPS 2.2.x with a relative URL (/somefolder) you need to edit your mainfile.php to have an absolute URL (http://www.example.com/somefolder) in the line
define(XOOPS_URL, "http://url");

Extra:
During the day, a number of people have reported problems when upgrading from XOOPS 2.0.x to 2.2.3 Final. This was caused by a faulty update routine which has now been fixed.
I have updated the 2.0.13.1 to 2.2.3 Final patch and 2.2.3 Final full package as well as the 2.2 to 2.2.3 Final update patch - just to be on the safe side. They now have a "2.2.3a-Final" in the filename. The version has not been incremented inside the package as this had only to do with the update routines and not the actual core files.

Those that have already applied the 2.0.13.1 -> 2.2.3 Final patch can download a hotfix directly from SF.net Tar.gz | .zip

Upload and overwrite existing files and update the System module through the administration or if that is not possible, re-run xoopsupdate.php from the XOOPS root.

When done, remove xoopsupdate.php from the XOOPS root.