Well, there's the real world answer, and the legal answer. Not too sure about the legal answer, thats always murky. Some things are copyrighted, some aren't. You can't just take someone's story, or art, and use it on your own site without permission. Usually the creator has all rights until they are given away. Even if they have uploaded it to another site, that doesn't mean they have given you permission though. On the other hand, some information can't be controlled. If Bob says it's 70 degrees in San Francisco right now, you can totally say its 70 degrees. If the Mets won, you're welcome to say the Mets won. The Drudge Report does nothing except report headlines.
In the real world, however, people steal information all the time. Its not polite though. Usually people ask for attributes. I don't think a policy of only removing it when someone asks you to would be polite. That's like stealing something when no-one is home and leaving a note saying you'll return it if they ask you to.
Also, pure scraping, even of non-copyrighted information can get you into trouble if the other person had paid for that information, like a news site. They pay for their news. Scraping it and making your own news site (with full content, not just headlines) is illegal.
So the short answer is that the original creator still owns the content, and no you probably can't have it.
What if the user is submitting content that they would very clearly want re-distributed? I guess my question with that is, if you take the end-user who is submitting the content out of the equation, does the site that is being scraped from have any kind of leg to stand on if they don't want you scraping their content (excluding technical means that they might implement), assuming that the site being scraped from does not force their end-user who is submitting the content to agree that the site that they are submitting the content to "owns" the content, once it is submitted?
The myspace suicide case really muddles this and makes it a problem. If the site you want to scrape from has TOS that say you can't re-use the info, (and it most likely would), then re-using the info would be a violation of the terms of service. Basically, in the MySpace case the feds are trying to make it a crime to violate a website's terms of service.
But like someone else said, if someone wants their content distributed, the user is not going to give you any trouble, and if they do, you're very protected if you take the offended material down right away, as someone else mentioned.
The website you're stealing from does have legal measures they can take, especially if you're directly competing with them. I think someone else mentioned that they could also just reconfigure their website to mess up your scrape, which is probably what they'll keep doing. They'll also likely publicize your bad business practices and you'll end up with a horrible reputation. Nobody likes a copier. Its like people who steal designs. They hardly ever outperform the website they're copying.
In the real world, however, people steal information all the time. Its not polite though. Usually people ask for attributes. I don't think a policy of only removing it when someone asks you to would be polite. That's like stealing something when no-one is home and leaving a note saying you'll return it if they ask you to.
Also, pure scraping, even of non-copyrighted information can get you into trouble if the other person had paid for that information, like a news site. They pay for their news. Scraping it and making your own news site (with full content, not just headlines) is illegal.
So the short answer is that the original creator still owns the content, and no you probably can't have it.