The pressure is on, and the record labels don't like it. Reuters reports that Warner Music Group and Sony BMG Music Entertainment are feeling increased pressure to follow EMI and Universal Music Group's lead in distributing music in the MP3 format, which forgoes restrictive digital rights management technology:

"A yearlong download promotion planned between Pepsi and Amazon is among several developments forcing WMG and Sony to consider the format, Billboard has learned. News of the Pepsi promotion, which is expected to be announced February 3 during the Super Bowl, coincides with Wal-Mart's ultimatum that major labels supply walmart.com with their music in MP3, sources said."

These are good signs for the mobile music market. We've been waiting for the other shoe to drop for some time now, especially now that Warner's CEO softened his stance on DRM.

Warner, Sony Feel Pressure to Remove DRM from Music [Reuters via PC Magazine]