I'm skeptical about how well suited a wiki is to original research. But I think it's extremely well suited to news summaries, a la Slashdot. Since there isn't really anything out there to do this, I think this will quickly become a huge success just for the news summaries. Maybe it'll work for original news reporting too, I think the current proposals on how to run things are necessary changes to the wiki model which are necessary for it to have a chance.
I do have a couple comments though.
"These stories will then undergo systematic review for another period of time, in which the editors try to find consensus."
I'm not sure it's reasonable to require consensus support for publication. I'd rather see a requirement that two or three accredited editors support an article, and they can be named somewhere in the article. Then, as long as there isn't a majority of opposition to the article, the article can stay. In theory there will be many more news articles in Wikinews than there are encyclopedia articles in Wikipedia. That's just the nature of news. I don't think it's reasonable to expect every news article to be a collaborative work of all editors. That's just not scalable. This is a fundamental difference between Wikinews and Wikipedia, and it needs to be addressed.
GFDL
There was talk about the impact Wikinews would have on Wikipedia, and a comment was made that Wikipedia will naturally copy Wikinews content where appropriate. But if Wikinews is GFDL, this isn't as simple as using copy and paste. It would be best if Wikinews contributors were asked to give permission for this from the beginning. This might take the form of "contributions made to Wikinews may be included in a derivative GFDL work so long as that work gives credit to the original author." Even this becomes problematic when copying news stories with multiple authors, but it's better than having to adhere to the details of the GFDL regarding history sections and title pages etc.
Note that the tempting solution of just using a different license altogether is probably not a good one, because Wikinews stories will likely benefit greatly from being able to include introductory text from Wikipedia, even if that does mean they then have to include a byline and history section mentioning the Wikipedia author(s).
Copies from VOANews and other PD sources?
One thing I'd like to do in Wikinews is copy some stories from PD sources such as VOANews.com and edit them. This doesn't seem to fall under "summaries from external sources", but I don't think I should be required to be an accredited editor to do this. I'd like to see it clarified that this falls under the types of news stories anonymous editors can create.
Anthony