It has been announced over on the EU PS Blog that a multiplayer Resistance 3 demo is on the way, but it is exclusive to PlayStation Plus subscribers.
“If you’ve checked out the US Blog, you will see that the R3 multiplayer demo will be accessible to SOCOM: Special Forces (aka SOCOM 4) purchasers in North America.
In PAL, this demo will be opened up to PlayStation Plus subscribers at the exactly the same time – additional info (such as how and when) will be unveiled in due course.”
We’ll keep you updated with any new information.
Source: EU PS Blog