After months of testing, Drupal 6 was officially released today, and I've already upgraded. There are a number of improvements and enhancements that will be of interest to news sites.
One of them is core support for user-configurable workflow through an interesting system of triggers and actions. For example, I quickly created a set that sends me an email any time anyone posts a comment on my website so that I can review it.
I previously had a special-purpose module that did that. With the new core support for triggers and actions, I can easily create my own sets that meet unforeseen needs by just filling out a couple of forms and pressing "enter." For example, I might choose to promote an item to the top of a page if it's getting comments, or change the publication status at a particular time, or block a bot that might succumb to a "honeypot" form.
Setup is radically improved, especially if you're installing from scratch, which is a breeze. If you're upgrading an existing system that has been heavily modified -- which generally is the case for large news sites -- there can be "gotchas," as there are major changes in some of the Drupal internals.
Theme development (page templating) is greatly improved, especially with the devel module, which is a separate module. It demystifies some obscure points of Drupal theming, much as Firebug does for HTML developers.
Other improvements affect large-scale site performance, usability, Ajax enhancements, permissions and scripted events.
All in, it's a greatly strengthened foundation and I know a lot of our tech guys are chomping at the bit to start migrating sites to the new platform. However, some critically important modules such as Views are still in a state of flux, so don't expect to see large-scale sites launching or migrating overnight.
As usual, the core developers are already hard at work on the next big version.