Not that we realised they were still open but Killzone 2 and 3's multiplayer servers are shuttering in March | VG247
Killzone 3 - Gameplay Multiplayer Online - HD - YouTube
Finished Killzone 2 on RPCS3, now playing Killzone 3. I never got to play this one when I had my PS3. Much better and more responsive controls than 2. System Specs: Legion
How to Play Killzone 3's Online Multiplayer Mode for PS3 « PlayStation 3 :: WonderHowTo
How to Play Killzone 3's Online Multiplayer Mode for PS3 « PlayStation 3 :: WonderHowTo
Killzone 3 - IGN
'Killzone 3' multiplayer goes free-to-play next week - The Verge
Co-Optimus - Review - Killzone 3 Co-Op Review
Trailer - KILLZONE 3 Multiplayer Killstreak - Bilgarsk Boulevard Video for PS3 - YouTube