Too often I see "progressives" (ie, Kucinich supporters, Greens, etc) calling for abolition of the Electoral College and also clamoring for IRV. The net result of adopting both changes would be to give power to fringe political interests and simultaneously degrade the representation of voters in small states and rural areas. A better cause for people concerned with fairness might be repeal of the 17th Amendment...
SDB's essays are essential reading to understand in clear terms why we must preserve the EC and never adopt IRV.
UPDATE: In response to a commentor who argues that the empowerment of the fringe vote is a feature, not a bug, Steven responds:
The basic question of whether minority political positions should or should not be able to influence the system is judgment call, a matter of philosophy. My opinion is that on balance the consequences would be more negative than positive, but it's not something which can be proved one way or the other.
Agreed that its partially a philosophical opinion, but I think the analogous economic philosophies would be Soviet centrally planned socialism and free-range Honk Kong capitalism. There probably is some middle ground. But the get-IRV/dump-EC combo would put us firmly at one extreme, whereas right now we are nowhere near the other end (though we'd get closer if we dumped the 17th amendment).
It is to an extent a philosophical issue, but one that has solid empirical support, if you consider European governance as an example. Any suggestion that our political system is unstable or ineffective is laughable compared to those. An economic analogy would be the difference in philosophy between centrally-planned Societ socialism and unfetterred Hong Kong capitalism. At present the American economy leans centrist with a strong HK (rightwards) tilt.
The political system we use also has a left-right spectrum, with abolishment of the EC and adoption of IRV forming the extreme far-left end. Whereas at the extreme right end, we would have no direct elections of our representatives at all (they would presumably be appointed by the State legislatures). Repeal of the 17th Amendment would be a recalibrating step rightwards, to the sweet spot defined by the Founders.