While Xbox 360 owners have been enjoying the hell out of Call of Duty 4: Modern Warfare's multiplayer, owners of the PlayStation 3 version like myself have been getting an altogether different definition of deep and hard. Players are reporting long wait times for matches, with connection issues plaguing servers once the matches do start. According to Inifinity Ward, the problem lies with servers getting slammed with far greater traffic than they had anticipated. Fortunately the PS3 server team is on the job.
The server team has been working on this all weekend, and will be working through the night. They're upgrading all server hardware as well as dedicated an individual database to each functionality to improve performance and handle the traffic hitting the servers.
Hurry up guys, I have embarrassing amounts of dying to do!
Update: PSN Matchmaking [Infinity Ward Forums]