and this is still posted by one person.

the versions of the post need bylines to follow your argument. maybe the usernames in the comments do that.

i don't think people cared about getting credit or how we found out, people wanted to know where mark was.

If the Twitter updates on Sean's original post are collaborative reporting (are they?)

It is collaborative networking. It seemed to me that all the "reporters" where members of the same circle of people. I think that "collaborative reporting" should be more used when people don't know each other and all report their views and impressions on the local happening event, being that information processed by one or more recipients.

what does this mean for community blogs and authorship?

Well! That is an issue with blogs and any piece of content on the web.

If you think that a blog requires people mentioning it (or at least its text contents) I think this could be "Fair Use" and good for the blog owners' propuses.

Even if the source is not mentioned, eventually, it will hit the crawlers due to many references to the contents or the original URL itself.

On Sean's case I think that the idea was to promote the fact in order to achieve a result and not to get credit for promoting it, right?

Is this community journalism?

I was taught that News have a format: What, Where, Who and, if possible, Why.

Being in Twitter hardly respond to that questions in a single text.
Is this (http://twitter.com/panasonicyouth/status/994447267#) journalism? I doubt!

I read the original article and it seems to me that Twitter was used as much as phone calls.

If you mean that the community as a source of information to a blogger as being "community journalism", it can be. But nowadays even "regular journalism" cite blogs (good example cited at http://www.wired.com/culture/lifestyle/news/2002/12/56978) and get information from viewers using cell phones, email, twitter and all the other available internet and media tools.

I think that community journalism is "journalism" made by persons that are not professional journalists, with means that are not traditional "journal" and that do not follow the full editorial rules and organigram (editor, reviser, journalist, etc et al) but use somehow a "journalistic" way of write the article, which Sean's one is a good example of it.

Is an internal school newspaper "community journalism" or just "regular journalism"?
What do you intend by "community journalism"? The same writen at http://en.wikipedia.org/wiki/Community_journalism ?

I am someone with an unusual perspective. I was in journalism, mostly daily newspapers, for 32 years and spearheaded one of the earliest news Web sites in the country (ohio.com). I have watched as conventional journalism has changed drastically -- not for the better, I might add -- and the world of Internet communities has exploded -- for the better, I'd add.

What I think we are witnessing is a transformation of the dissemination of information. That's not exactly a new observation there, but the question I always have in my mind is how do we know whether the new material -- posted on blogs and community sites -- is accurate, fair and real? Is it true?

Traditional media sources had, despite their shortcomings, the advantage of professional editing and fact-checking. It had an editing process: How do we know this? Is it fair? Does it make sense? Have we talked to as many people as possible who have direct knowledge? Have we examined the potential contradictions? Do we have supporting material?

So to me, a community blog post is something that does not carry the weight of a traditional news organization. It must, by nature, be taken with a grain of salt. I presume that the writer or the photographer or the videographer is NOT a professional and so, therefore, has not followed a process to ensure accuracy and fairness and quality.

But that does not take away that it can be compelling and, in some cases, more true, more real than what we see in conventional media.

And one additional point -- the processes used by traditional news media can sometimes constrain the truth. How? Rules of slander or libel; the news paper's own rules of ethics -- what it will publish and what it will not; the news organization's desire to get "both" sides; and, sometimes, that the information will cast an advertiser in a bad light -- that type of story is, in fact, sometimes set aside or subject to extraordinary scrutiny or gutting in order to be "fair." Rules and practicalities sometimes get in the way of truth.

All this is longwinded context to my answer to your perfectly straight forward question...

The difference between a community post and a newspaper article and a Web posting on a news site and a newspaper article itself is this:
The newspaper article has had more rigorous editing and vetting; sometimes this will result in the exclusion of unsupported detail that would aid in understand and, in the need for balance, an unbalanced presentation of truth.
The community post is apt to present a one-sided view and has not had the advantage of professional news gathering experience and the editing/vetting process. However, sometimes the one-sided view is the clear expression of a witness to fact.
The news Web site posting done by a staffer carries much of the same professional stamp as the newspaper article and can often include much more information that allows for complete understanding of a story. .... If the piece is done by a citizen with no vetting whatsoever, I'd argue that's the worst of the lot because you, as a reader, don't immediately know that and assume it to be true.