The advantages and disadvantages of carbon sequestration depend in large part on the methods used. Capturing CO2 gas and piping it underground is, as another answerer suggested, risky and probably inefficient. But other methods may hold more promise. For example, using algae to sequester carbon, then burying the algae, eliminates the problem of the tendency of a gas to escape confinement. The major advantage of employing some kind of carbon sequestration technology is that it can, in effect, reverse some fraction of our bad habits with regard to CO2 emissions. Unless we find some way to sequester massive quantities of carbon more cheaply than the difference between fossil fuel technologies and renewable energy technologies, it won't give us carte blanche to keep using fossil fuel, but it can help reverse some of the past damage and/or help us ease the transition to newer tech.
As far as I'm aware, clean coal usually does not refer to the CO2 emissions of the coal, but instead to the particulate emissions and the like. As such, while it will significantly reduce local pollution problems (relative to traditional coal technologies), it will have no direct effect on global warming. In fact, it may indirectly make global warming worse, because the absence of a smelly plant belching nasty black smoke may make people less willing to switch from coal to renewable resources like solar, wind, and biomass.
Jyush, look up marine cement... we can make carbon-neutral concrete today. Depending on the engineering characteristics needed, we may even be able to make carbon-negative concrete.