tl;dr version: RH always sends out a press release about Fedora releases. But usually, Fedora sends one out *first*, and LWN would usually run the Fedora announcement. This time, we screwed up and didn't send out a Fedora announcement, so the press release from RH was the first thing LWN got, and they printed that.
Long version follows:
Red Hat PR always sends out a press release when a Fedora release is done. This isn't at all new for F18. Those of us RHers in Fedoraland do kind of regret the fact it tends to result in a flood of news stories saying 'Red Hat announces Fedora XX...', but it seems really hard to stop this happening. Note that the RH release is worded much better than it used to be, based on suggestions from Fedoraland people: it now explicitly says "by: The Fedora Project Team" and "The Fedora Project team is excited to announce the beta release of its free, fully functional Linux operating system, Fedora 18, code-named “Spherical Cow.” (i.e. it doesn't credit or even mention Red Hat, as it used to).
What happened differently in this case is not that RH sent out a press release - as noted, that always happens - but that Fedora neglected to send out its own release announcement. The Fedora announcement usually comes out some hours before the RH one and so most Linux sites carry the Fedora announcement; only very enterprise-y and general tech-y sites, which only take RH's PR wire and aren't plugged into Fedora announcements at all, usually run the RH release.
Unfortunately, Dennis Gilmore (who'd usually have sent out the announcement) was out today, and Kevin Fenzi (who ought to have been the backup) was at a FAD. All the rest of us thought someone was else was arranging to cover the release announcement, and it turns out no-one was. Just a SNAFU, nothing more sinister. We're now trying to throw together an official Fedora announcement quickly.
Don't panic, everything is fine, and the facehugging aliens absolutely will not be able to escape from containOHMYGODITBURNS