What's the standard Libertarian position (if there is such a thing) on IP and patents?

Well, I don't know if the LP has a plank on IP, but they're pretty much irrelevant to the libertarian cause at this point. Libertarianism, as you might expect, doesn't really have a strong consensus on the subject. From what I've seen, however, the more "hardcore" a libertarian is, the more skeptical of and/or opposed to the concept of "intellectual property." (Cf. this excerpt from one of Hayek's writings.) More moderate libertarians tend, in my experience, to support narrowing of the definition of IP and shortening of protected periods. The reason being that IP law is fundamentally a mechanism for government-sponsored monopoly, and that broad definitions and long protection terms serve only to stifle the very innovation that IP law was created to encourage.

Here's a nice quote on the subject from a famous libertarian extremist:

"Stable ownership is the gift of social law, and is given late in the progress of society. It would be curious then, if an idea, the fugitive fermentation of an individual brain, could, of natural right, be claimed in exclusive and stable property. If nature has made any one thing less susceptible than all others of exclusive property, it is the action of the thinking power called an idea, which an individual may exclusively possess as long as he keeps it to himself; but the moment it is divulged, it forces itself into the possession of every one, and the receiver cannot dispossess himself of it. Its peculiar character, too, is that no one possesses the less, because every other possesses the whole of it. He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. That ideas should freely spread from one to another over the globe, for the moral and mutual instruction of man, and improvement of his condition, seems to have been peculiarly and benevolently designed by nature, when she made them, like fire, expansible over all space, without lessening their density in any point, and like the air in which we breathe, move, and have our physical being, incapable of confinement or exclusive appropriation. Inventions then cannot, in nature, be a subject of property." -- Thomas Jefferson