Is it legal to post an IM conversation?

I’m of the mind that there is no law against posting an instant message conversation you’ve had as both parties involved pretty much know anything being said can just be saved and posted anywhere. But am I wrong? Is it illegal to post an IM conversation?

From what I’ve heard, as long as it’s not libelous in nature it’s ok to do. Also, there are many humor websites that host funny aim converstations all over the net.

Technically, the people involved hold copyright and you can’t post it without their permission.

Realistically, though, it’d cost too much in legal fees for them to do much – unless they register the copyright.

How does registering the copyright make enforcement cheaper?

Technically, courts will accept registration as prima facie evidence of the validity of the copyright. So it just cuts down on how much money you need to pay your lawyers.

I don’t know of current case law, but I’d assume that IM conversations are protected the same way a letter or email is. The sender holds copyright, and the contents cannot be reprinted without permission. This is no different than here at the Dope, which prohibits non-fair use duplication of posts outside the context of the boards.

IOW, reprinting IM conversations is massively illegal in theory, no law exists to confirm this, and most people don’t give two hoots. Someday, however, there will be a significant court battle over this and people will get all inflamed because they’ll make the assumption that the OP did.

There is a site that has adults pose as minors in an attempt to lure people via IM to a location where they think they are going to have sex with an underage person. (As seen on a national newsmagazine show, you can figure it out)

They have dozens/hundreds? of IM’s posted, obviously without permission of the other party. There is also an “anti” site, that while very much against that practice, has never mentioned illegality of posting IM’s as a way to achieve their agenda, and I would think they would use that if legally possible.

Just a data point, I know nothing about actual law in this area.