A person whose behavior is antisocial and who lacks a sense of moral responsibility or social conscience.
With the Blagojevich scandal in Illinois, the word "sociopath" is being thrown around a lot. Partly, this is being done as a future defense against any "disclosures" that he may make in implicating the politically powerful of Illinois and, just maybe, Washington. By making him seem a little crazy, other politicians feel that they are inoculated against any Blago accusations.
Certainly, you can point to a Blagojevich as a sociopath because he apparently has little or no moral compass based on his actions over the last few weeks. His little speech the day before he was arrested could easily be said to be "sociopathic" by its very nature (See that Video). But, this is what all politicians do. They are almost always on the defensive and they can either use their words as swords in their defense or as tools to sell their snake oils. If they aren't outright lying; then, they are twisting the facts in any way possible to elicit support from those that are listening to them. Their whole life is spent blurring the lines between truth and falsehood. That's what politics is all about.