It looks like the upcoming SimCity remake may be the first step in a larger campaign to restore the luster of Maxis' Sim franchise. (Outside of The Sims, of course.) EA has filed a European copyright for SimOcean, which means it may be the first offshoot of the new SimCity.
In the days before The Sims re-branded the entire franchise, Maxis made a whole series of Sim games ranging from the focused micromanagement of SimTower, to controlling the path of evolution in SimLife. SimOcean would be a completely new Sim-experience, presumably putting players in control of an undersea ecosystem... or something else set in a large body of water.
Since SimCity isn't coming out until 2013, I wouldn't expect to hear too much more about SimOcean for at least a little while.