The remedy for this is registration of the copyright, which allows statutory damages for each act of infringement. This is a problem. The site would have to file as a published database each quarter. This wouldn't protect the posts. In order to get the benefits of registration, the copyrights must be owned by the registrant. All text not so owned isn't registered. It's pretty clear, one registration - one owner.

So posters either have to live with the problem, copyright their contributions themselves (they can register a group of the as long as they all have the same owner) or assign the rights to the legal entity that owns ip-wars.

In the last, case ip-wars would grant the author a perpetual, irrevocable, non-exclusive license to any and all non-exclusive rights, including the right to sublicense on the same terms. The conveyance could be done by specific assignment, probably generic assignment if it was clear what was being conveyed and signing of a work for hire contract, cancellable at will.

The last would be the easiest. It's bulletproof and only has to be done once. It has to be in writing, so you'd have to print out a form from the site, fill it in and mail it.

In the case of the contract, there has to be consideration. The traditional "1$ and other valuable considerations" would do, but who wants to mail back all those 1$ checks. It may be that protecting the messages by registering them would be sufficient consideration if the author had a net share of any recovery. This would make the consideration monetary and probably beyond challenge, though I'm not sure a third party would have standing to challenge the contract.

If a reasonable minority did this, it would make infringement very risky unless you knew which pieces were copyright to ip-wars. Since everything on the site has the same license terms, this might be kept secret. There would just be a statement that ip-wars held the copyright to some of the messages.

So how many people are concerned enough about violations of the site license to be in favor of something like this - either in the abstract or because they'd like to assign their messages?

I'm not sure I am, but it looked like the time was ripe to discuss this.