Good news, everyone!
Many people use OpenVZ on Debian. In fact, Debian was one of the distribution that come with OpenVZ kernel and tools. Unfortunately, it's not that way anymore, since Debian 7 "Wheezy" dropped OpenVZ kernel. A workaround was to take an RPM-packaged OpenVZ kernel and convert it to .deb using alien tool, but the process is manual and somewhat unnatural.
Finally, now we have a working build system for Debian kernel packages, and a repository for Debian Wheezy with latest and greatest OpenVZ kernels, as well as tools. In fact, we have two: one for stable, one for testing kernels and tools. Kernels debs are built and released at the same time as rpms. Currently we have vzctl/vzquota/ploop in 'wheezy-test' repository only -- once we'll be sure they work as expected, we will move those into stable 'wheezy' repo.
To enable these repos:
cat << EOF > /etc/apt/sources.list.d/openvz.list
deb http://download.openvz.org/debian wheezy main
deb http://download.openvz.org/debian wheezy-test main
To install the kernel:
apt-get install linux-image-openvz-amd64
More info is available from https://wiki.openvz.org/Installation_on