From Call of Duty World at War XBox 360 forum...
So as you know, Map Pack 1 is releasing shortly (March 19th) or has already released depending on when you read this. With it, a new TU / Patch is being released for the Xbox 360 and Playstation 3.
We have been reading many of the suggestions in the community rgarding improvements to the game, and hope that you'll find many of them in the list below. I think the most popular item in this list will be the improvements to the spawn system included in this TU =).
* All rifle grenades fired during the first 15 seconds of Search & Destroy will be duds to prevent griefing in that game mode.