In an interview with CIO magazine Steve Ballmer confirmed the Zune Store will be coming to Windows Mobile.  When asked why Microsoft created the Zune Ballmer replied, "At the end of the day, one of the big trends is that all content is going digital. And if we don’t have the software and services that are useful, helpful and valuable for the consumption of music and video, we are sort of not really a player.

Now, we built the Zune hardware with the Zune software - and what you’ll see more and more over time is that the Zune software will also be ported to and be more important not just with the hardware but on the PC, on Windows Mobile devices, etc."

Source: Engadget via WMPowerUser via CIO Magazine