Mobile music is making a big noise at the MIDEM conference in Cannes this week. Device manufacturer Sony Ericsson so far has made the biggest splash with a major expansion of its PlayNow initiative to include more than 5 million tracks.

The increase comes via partnerships with 10 record labels and digital aggregators. They include majors EMI Music Group, Sony BMG and Warner Music Group; digital aggregators The Orchard and IODA, mobile aggregator The PocketGroup; and global labels Hungama, X5 Music, Bonnier Amigo, and VidZone.

The PlayNow service allows users to preview and purchase full songs, ringtones and other mobile content, including mobile games. It also offers new and unreleased music from emerging acts being promoted by its label partners. It's available initially in Sweden, Denmark, Norway and Finland this May, with more European countries coming online this summer, and expansion into Asia and the Amercias by the end of the year.