Lets be honest, if you own a PS3, then you're probably pretty pumped up for Killzone 3. The upcoming FPS (February 22nd) not only looks fantastic but is the flagship for shooters on the console and one of Sony's biggest guns.
You more than likely don't need access to the beta of third-person (and Move enabled) action title SOCOM 4 to sweeten the pot- but you're going to get it anyway. Pick up K3? Get the S4 demo. Simple.