The PlayStation blog reports that the multiplayer beta for Killzone 3 begins October 26 -- and it's only open to PlayStation Plus subscribers.
To join the beta, PlayStation Plus subscribers should download the Killzone 3 XMB theme from the Plus section of the PlayStation store. The first 10,000 who do so -- 5,000 America subscribers and 5,000 from Europe -- receive access to the beta.
The beta is also open to certain members of the media and a selected group of PAX feedback participants.