Gaming is mainstream and growing, this is obvious to most video game enthusiasts. Even Jack Thompson has failed in taking down the industry in his efforts on video game violence and general FUD. In order to survive in a mainstream environment publishers and developers are going to target a broad demographic to make them as much money as possible.
Soon we'll start seeing more spouses changing their tune from, "games are stupid" to "let me try." As one of our podcast hosts found in episode 95 of our Gaming Podcast during his review of LittleBigPlanet, his wife pulled the controller from his hands to give the game a try and… liked it. As member ATC 1982 found when trying the Kingdom of Keflings demo, the family might actually like the game which could, in turn, cause him to purchase it.
Mainstream isn't your dad playing a video game in the basement after the kids go to bed, it's replacing Sorry with Spore and bringing out Wii Sports and having little family tournaments.