No, but also yes. You will receive 5 years support on packages Ubuntu provides support for this term.
Lubuntu shares packages with Ubuntu in a sense that "underlying" "base" software like Alsa, the kernel, common shared libraries and such are from the same archive and maintained by the same people. Lubuntu is nothing more than Ubuntu with another set of preselected set of packages. It's just that Unity comes with 5 years of support and LXDE doesn't, in Ubuntu.
For the example of the kernel, Unity and LXDE core, run this on Lubuntu 12.04 or Ubuntu 12.04 (won't make a difference):
$ apt-cache show linux-image-generic | grep ^Supported
$ apt-cache show unity | grep ^Supported
$ apt-cache show lxde-core | grep ^Supported
This way, you can check for every package whether it comes with the 5 years of support or not.
So, this makes me disagree with the other answer stating
Also, please note that if you are using Lubuntu, instead of Ubuntu, you will not receive LTS since Lubuntu 12.04 isn't an LTS release.
Because, regardless of how you installed Lubuntu1, you will receive updates for 5 years, yet not for all of your packages (including LXDE).
1 You can install Lubuntu in two ways. 1) Install regular Ubuntu first, replacing Unity with LXDE via the
lubuntu-desktop^ apt-task and selecting it in your login screen as desktop environment to log in to, or 2) using the Lubunu Live CD/installer directly.