According to many of the images at tacitus.com / images, Tacitus is focused in computing. Not only that, but specifically computational biology. The Roman Tacitus is most likely not linked to any of this, however there is an image of him on the Tacitus images page. TACITUS is also an abduction-based system for text understanding, developed by Jerry R. Hobbs. Hobbs was a leading researcher in the fields of computation linguistics and artificial intelligence.He was employed at the Artificial Intelligence Center at SRI International from 1977 to 2002. In 1986, Hobbs published "Overview of the TACITCUS Project." I encourage you to read it, though it may or may not pertain to this Tacitus. It is note worthy however that the Tacitus in question does specialize in the same fields as Hobbs, who developed the Tacitus system. The Tacitus Project logo is called a toroid, though I don't know specifically what kind. It is peculiar how it resembles the Treyarch logo. Also, the odd looking circle symbol on all of the classified images on the Call of Duty page, I believe that has something to do with computing, and computer chips. I don't claim to be avid in computing, however the symbol does look a lot like the cover of Pendulum's "In Silico" So, in short, I'm getting a very biotechnological feel from all of this. Not to mention, the mix of biology and computer technology, in terms of storing and retrieving data, ties in rather well with the storyline of Black Ops. As you may recall, Mason held the numbers within his mind, much like a biological computer. Tacitus as a military controlled Artificial Intelligence research group in the BO2 story would make a lot of sense, whether Tacitus.com actually has anything to do with it or not.
P.S. - search "tacitus project" on Google. Click the first link for "Overview of the TACITUS Project"