I cannot recall exactly where, but I recall an event where a lake in a large volcanic crater built up a pocket of carbon dioxide in it - then, in a sudden out-gassing, it suffocated all life in the region.
Although not a geophysicist, I suspect such an event could not happen in most carbon sequestering scenarios. However, I do understand how entropy works, and I wonder what influence the dispersion of artificially concentrated concentrations of carbon dioxide would have on the local sea life.
Furthermore, carbon sequestering fails to address two key issues for me: resource use and efficiency.
Since my focus is on sustainability and not environmentalism, I am concerned that carbon sequestration will actually increases our resource consumption. As dissenters point out, you must use fuel and a portion of your generated electricity during sequestration. Compare this to cleaner alternatives where the waste stream lies mainly in the manufacture of the power plant, and thus no energy is diverted to deal with byproduct of energy production.
Also, if anthropogenic carbon emissions do alter the climate (and the vast majority of scientists, especially those in the field, do agree that it does), carbon sequestering does nothing to decrease our usage of electricity. In fact, it may justify a lack of concern in users. ("Hey, all the bad carbon dioxide is safely stored - so its okay to use as much energy as I want. After all, its 'clean' energy now.")
I would much rather see an efficiency program adapted versus a sequestration strategy - of even better, both (but that most likely isn't fiscally viable). Greater energy efficiency and lower power consumption should be the primary goal.
To keep this tied in with IT, lets use the data center scenario. Which capital investment would benefit a company more:
1) going to a virtualization platform where physical servers can host multiple virtual servers to maximize system resources, thus allowing physical systems to be dynamically switched on and off as needed and virtual systems to be migrated on demand. (This also add the benefit of fault tolerance.)
2) paying their utility company a premium to cover the cost of carbon sequestration and thus improving their "green image" by reducing their impact on the environment.
Of course, most businesses would probably choose the second because of short-term thinking. The first option requires a high initial investment compensated by monthly savings, the second requires a small monthly expense that will keep accruing. Now, instead of money, think of efficiency versus sequestration in terms of net carbon dioxide emissions. Which one would have the greatest cost-benefit ratio after 5, 10, 50, or 100 years?