To quote the NY times (
http://www.nytimes.com/2004/04/15/business/media/15real.html?hp):
RealNetworks Seeks Musical Alliance With Apple
By JOHN MARKOFF and STEVE LOHR
Published: April 15, 2004
RealNetworks made a direct appeal last week to Apple Computer, its Internet music rival, suggesting that the two companies form a common front against Microsoft in the digital music business.
The offer to create a "tactical alliance" was made on April 9 by Rob Glaser, chief executive of RealNetworks, the Seattle-based Internet music and video service, in an e-mail message to Steven P. Jobs, Apple's chairman.
But if an alliance with Apple could not be struck, Mr. Glaser strongly hinted in the e-mail message that he might be forced to form a partnership with Microsoft to pursue "very interesting opportunities" because support for Microsoft's media-playing software seems to be growing.
...
In his message, which was obtained by The New York Times from a person close to Apple, Mr. Glaser asked Mr. Jobs to consider licensing Apple's Fairplay digital rights management system to RealNetworks to permit customers of the RealNetworks music service to play their digital music collections on iPod players.
In exchange, RealNetworks would make the iPod its primary device for the RealNetworks store and for the RealPlayer software.
The message notes that both RealNetworks and Apple support the same digital music technology standard, known as AAC. But because it is not possible for RealNetworks' encrypted music services, Rhapsody and the Real music store, to be played on iPod, RealNetworks is considering switching to Microsoft's competing WMA format, which would make the RealNetworks services work seamlessly with Microsoft's technology.
"We are seeing very interesting opportunities to switch to WMA," Mr. Glaser wrote. "Instinctively I don't want to do it because I think it leads to all kinds of complexities in terms of giving Microsoft too much long-term market momentum."