Yes, the biggest addition to Slackware 13.0 is probably the official 64bit port of Slackware. "While the 32-bit (x86) version continues to be developed, this release brings to you a complete port to 64-bit (x86_64)," Patrick Volkerding writes, "We know that many of you have been waiting eagerly for this, and once you try it you'll see it was well worth the wait."
Furthermore, it comes with Xfce 4.6.1, KDE 4.2.4, Linux kernel 126.96.36.199, and continues to use HAL. On the developers' side, it comes with gcc-4.3.3, Perl 5.10.0, Python 2.6.2, Ruby 1.8.7-p174, Subversion 1.6.4, git-1.6.4, mercurial-1.2.1, graphical tools like Qt designer and KDevelop, and more.
Download information can be found in the release announcement.