Debian does commit to security support for packages in main, i expect they will backport the patch to their current version and send notification from security-announce when an update is released. Also keep an eye on https://security-tracker.debian.org/tracker/CVE-2013-4547
You can either use the Phusion Passenger one: https://www.phusionpassenger.com/install_debian
Or the Nginx.org one: http://nginx.org/en/linux_packages.html
Both support Debian 6 and 7, and both supply the latest Nginx stable version.