Marcus of Washington Syndrome, in a response to Jack Balkin's new article (which I promise to read and comment on, but you've heard those promises before, I know), sets out the dilemma of originalism with great pith and no little substance here.
In short, to the extent we identify meaning with expected application, originalism would result in terrible things. To the extent we separate meaning and expected application, originalism has no force at all. If we seriously tried to apply "liberty" as the Framers would have applied it, we would provoke social revolution. If we say the meaning of "liberty" does not change when we apply it differently (which makes sense to me), then originalism provides no solution to the problem of judicial discretion.
Personally, I accept the "separate meaning from expected application" side of the fork. In Canada, at least, no one really wants the other side of the fork, since that involves trying to read the mind of Jean Chréien circa 1981, not a task anyone ever thought would be rewarding. But that means I have to find some other basis for avoiding judicial tyranny.
Update: Looking further at Marcus's blog, it seems he has been advancing these sensible ideas and distinctions for some time. I guess the point that originalism and the living constitution are perfectly compatible has been out there in the law school world for some time, since I can't really recall where I picked it up. I do recall reading Scalia in A Matter of Interpretation accepting Dworkin's distinction between semantic intent and whatever-he-called-the-bad-kind-of-intent, and realizing that the game was up.