Another way would be posting something as DRAFT and updating that root node. To prevent that root node to fall into oblivion update notes could be posted as replies.

IIUC, this is a sort of variation on the first scheme I mentioned: it is interesting and efficient. But I fear it may cause some problems with replies from other people, if people are supposed to discuss the topic. Now that I think of it, for maximum efficiency -and depending on the actual kind of content- one could take a third approach consisting basically of both:

• the user, e.g. me posts an umbrella node with an indicative title, e.g. "blazar wants to do it" and explains there the stated goal of the planned series of articles, asking people to please do not post followups directly under that thread;
• he posts the first article as a separate root node in the appropriate section, with a title like "blazar wants to do it - part I: conquer the world (DRAFT)". He puts a link to the umbrella node and a link in the umbrella node, to the draft;
• after hundreds of monks contribute their words of wisdom about how to conquer the world, the user will want to update the original draft with all of their suggestions. Thus he will post a direct reply under the umbrella node with the finalized version, putting there a link to the draft version and vice versa;
• and so on for the other articles...

Sounds complex, but it sounds more than it actually is. It allows for separation between user discussions and nicely presented material. It is weak in that it depends on good will on part of "others" and however carefully you try to state something in an idiot proof manner, along comes a better idiot. But all in all I'm confident that as a scheme it would be robust enough. And yes: it allows for some DRY violation but not in an upsetting manner, IMHO.