Right, Noticed there's a bit of confusion on the forums since the title update hit yesterday (thank you SCEE for releasing it early to euro ps3 players) so heres the cliff notes. (examples have been simplified)

This title update is not meant to "fix" the numerous omg lag comp i hate you complaints. What it was meant to do was change the way parties matchmake and in theory by doing so create and place parties into better quality matches. The knock on affect for this for solo players is there should be more localised sessions available to you and you may find the overal gameplay expereince is improved to what degree also depends on the connection qualities and a few other varaible,s

The old system matched parties based on EVERYONE in the parties ping, put simply if you played with friends who were geographically spread out the game would try to put you in a session so everyone in that party had an equal ping too, this meant you usually ended up being placed in lobbies further afield than most would consider "local".

For example a party of 6 friends 5 of whom were local and one who was miles away might find their pings were 5 at 50ms and one at 100ms , as such the game would most probaly put you into a session based on a 75ms ping.

Under the new system matchmaking only takes the party LEADERS ping (thats in game party)

so using the same 6 players..

if one of the 5 who were closest together were given party leader the party would be placed into a session local to them and the 6th guy would be most likely 3 barring. Why this is better is there is less latency between players which makes for a smoother gaming expereince and as such the dreaded oft misunderstood mechanisms involved in what people commonly refer to as "lag comp" aren't working over time on more players in the session.

Put simply the onus is on the party to decide who would be the best party leader based on the parties location.

Capp00 and myself made a video that explains this in greater detail with pictures!!! (please bear in mind due to the time differences i was half asleep (we recorded it at 5am my time) so please excuse the zombie like accent and ramblings from myself i was frantically downing coffee to wake up .

There is still more tweaks and faffing coming from IW in the future, as they are looking through all the netcode to try to find areas they can tweak /change to benefit players by comparing mw3's netcode to all changes made to it since mw1 so consider this step one in a longer process.