Xbox Live socialistas were upset by Modern Warfare 2's policy of prohibiting players from taking part in certain online multiplayer modes while in a Live Party. In a recent interview with Videogamer.com, Treyarch's online director Dan Hunting explained that this policy returns in Call of Duty: Black Ops, reminding players that "we have that same restriction in certain playlists where they can use party chat to exploit the game mode." The hardcore Search and Destroy gametype is used as an example of where this would be appropriate.
However, the restriction won't be applied to as many playlists as it was in last year's Duty, including Team Deathmatch and "any game mode where it doesn't make sense to have it." So, yes, certain game modes will still require you to converse with the hoi polloi, but isn't that part of the magic of online shooters?