That originally made them the first Linux distro to be CC-Certified, beating out Red Hat (which is by far the more common distro).
But now, SuSE has raised the bars and become EAL3 certified, once again in tandum with IBM. Even though IBM is partners with both Red Hat and SuSE, it seems to be going in favor of SuSE. Once again, it seems that SuSE has beaten Red Hat in terms of becoming certified.
See Suse's press release here.