Matchmaking has been a big topic lately, and most people here want changes from what I can see. This late into the release of Uncharted 3, I think simplicity is important in the ideas we give to Naughtydog because they are obviously busy on other things. This is the reasoning for my very simple idea for a change that could greatly improve lag.
When start searching for a game, from what I can remember, it starts on "searching for Optimal game." Now I don't know a whole lot about how matchmaking works, but I would guess this is ping based or something similar. The problem is that it only stays on it for about ten seconds before switching to "searching for close game." Then after a few more seconds, we see "searching for any game" and prepare ourselfs for lag. (correct me if I'm wrong about the order or if I missed a matchmaking step) My point is: why can't we search for an optimal game for a longer amount of time before switching to the next step down?
This doesn't have to be the only thing done to reduce lag, combined playlists would aso help a lot (idea from tapantaola). This is just one simple thing to change, that I think could have a good effect on quality of matches with no negative effects at all.