Thumbplay confirmed today it has signed a deal with Warner Music Group (NYSE: WMG) to add content from artists such as Kid Rock and Missy Elliot to its catalog of ringtones, graphics and videos. The content started to appear on the site this week, and a Thumbplay spokesperson confirmed today that it indeed has signed a deal with the music label. The first batch will be uploaded to the site this week and a second will go live next week. With the addition of Warner, Thumbplay now has content deals with all four of the largest music labels, making it one of the only content providers in the mobile industry to do so. However, none of Thumbplay’s deals are exclusive, so it may only be a matter of time before the others catch-up. For instance, Nokia’s (NYSE: NOK) Comes With Music service signed a partnership with Warner Music Group earlier this month, adding to agreements with Sony (NYSE: SNE) BMG and Universal Music Group. But Nokia does not currently work with EMI.