iTunes Radio is officially going to be released this September although many people still believe that it will be debuted next month in connection with Apple's latest iPhones refresh. iTunes Radio will be a free program for the consumer to use, but will have audio advertisements appear every 15 minutes, while a video advertisement will appear every hour.
In January 2014, ads on iTunes Radio will become available to advertisers via iAd with a minimum buy-in of around $1 million and will come in three forms (interstitial audio ads, video ads, and slated ads. So if you'd a small record label, start up or anything in the Music Industry you may have to wait some more time before you can advertise on iTunes Radio.