i thought that to be the one obvious position. the other (imho) equally obvious position seems to be the following:

copyright is protection of intellectual property, and securing property rights is the prime reason for goverment to exist.

according to the second position (and taking opposition to the estate/death tax into account) it seems consistent with a libertarian position to argue for infinite copyright terms.

am i wrong? i am not a libertarian, but i try to understand you folks.

There are some people who have argued for infinite copyright terms or perpetual ownership over every utterance they make. Rand argued for IP, saying (roughly) "a man has rights to the product of his mind."

In general though, I think the modern consensus in Libertarian circles has fallen on the side of opposing or greatly limiting IP in general. See http://wiki.mises.org/wiki/Intellectual_property for a reasonable overview.