callofduty.com has published a blog entry from developer Infinity Ward / Sledgehammer detailing some of the features and improvements that will be in the upcoming MW3, to be released on November 8th:

I'm extremely excited about the PC version of Modern Warfare 3 this year, because we've been taking your feedback since Modern Warfare 2,and the franchise as a whole, on what you wanted to see in the PC version of Modern Warfare 3 and the team at Infinity Ward and Sledgehammer Games has put aton of emphasis on delivering a PC experience that brings in all the great things we added in Modern Warfare 2:
Lobby System, Matchmaking with a Party, Matchmaking for Public Games, Steam Integration (Friends List, Server Browser,Achievements, Join on Friends)
While combining it with your favorite features from Call of Duty 4: Modern Warfare:
Dedicated Servers (Join your favorite or set up your own,without any 3rd party hosting requirements), In-game Server Browser that allows you to filter by ping, map, gametype, hardcore, voice, password, and more. In addition, we're supporting PC specific features that give you even more control over your experience like RCON, Custom Game Saving, NoGFX / Audio Card Requirement on DS.exe, Voice Chat, and SSAO.