I know this thread is a little old, but hopefully the original poster will see this:
You want Coranto. Right now. It does everything you asked and more. In fact a vbulletin comments addon was just finished after several of us tested it out over the weeks.
Not to get into the whole story, BUT - The creator of Coranto, Elvii, disappeared several months ago. Since then, the official website has gone offline with only a cryptic message saying Coranto would be released as open-source software.
Long story short, a lot of us have banded together and gotten the ball rolling. The "unofficial" site is now at:
http://coranto.gweilo.org
with forums, downloads, and more. You can download all the original Coranto files again. You can download a bugfix patch that was developed by the community (the last update Elvii made was 9 months ago, and it was still in a beta state). Best of all, there are MANY third-party addons for Coranto, and since the base program has an excellent addon-interface, installing said addons is a total snap. I can only hope vb does something like it for version 3.0 - that's how good it is.
Like I said, there is an addon for automatic vbulletin thread linking - it will automatically create a thread in the forum(s) of your choosing via the username of your choosing, create a link BACK to the news story you are linking from, etc. It will even update and/or delete the thread when you update and/or delete the news story in question.
There are many other addons as well. I did a spellchecker one that is partially based off the spellcheck hack Parker Clack posted about here. There is also a mysql addon so all your news can be database-driven (default is pulled from a flat text file, which is actually much faster for smaller sites).
I cannot say enough good things about it. Coranto is far and away the best news poster/CMS system I have used - and I am including expensive ones you have to pay for (Coranto of course is totally FREE). I use it for all the news on my site, as well as a review and article system. You can see it in action at
www.maximumgamer.com - note the comments link, like I said that is all done AUTOMATICALLY with vbulletin. I'm still working on cleaning up the styles and such but you will get the idea.