i'm having the same problems, but not during gameplay, its when it goes from the main menu into the game, as soon as the ps3 sign comes on, it goes all staticky and shit and makes wierd noises, but when the start up menu on the game comes, the static goes away, i thought the hdmi cable was a cheapo, since i got it free w/ a dvd player, but i havent tried another one out...
also, on the main menu, it says resolution is at 1080i but when the games on it goes down to 720p, but i figured thats what the game supports so i didnt think much of it untill some of you said that your gameplay is at 1080i, could it be something w/ the ps3 thats messed up, its not the tv as it supports 1080i and 1080p