The Entertainment Software Rating Board has been around for 15 years now, overcoming an ineffective start and a host of controversial events to become a fairly well-respected ratings agency. However, as this article at The Escapist points out, the world of video games is changing, and the ESRB does not seem to be adapting along with it
"The most pressing problem is the ESRB's reluctance to address online interactions. Seeing as we're moving more and more toward online and internet-enabled games, this inevitably limits the ESRB's authority as a ratings board. Although the ESRB rates the submitted developer content within online games, these ratings are always qualified by an important disclaimer: 'Online Interactions Not Rated by the ESRB.' To date, this has meant that the rating given to the designed game content doesn't cover chat and other forms of player-to-player communication. That's unfortunate, because the ESRB's intimate relationship with the game industry could provide it with a unique vantage point from which to evaluate aspects of online games that are beyond the purview of other would-be raters, including the quality of the game's moderation system, programmed restrictions on chat and known player demographics."