Hope this helps
For anyone having problems connecting to friends in MW2 before the patch on Friday I came a across an untested solution for joining friends parties...
To fix the problem simply:
Send your friend an invite
Tell them not to accept it, but instead to press the PS button and go to account management, then hit triangle. This bring up an option to log out. Do it.
Get them to log back in again
Tell them to accept the invite
Hey presto you’re in the same party!
Original source from bangbangtech.
I will be testing this tonight and will confirm or deny this.
Hopefully this works
Hi everglow21 the answer is yes, you will have to update your firmware to play MW2 on the ps3.