At one time you could drag and drop Zune DRM files onto a Windows Mobile Device and have it playback until the timelimit DRM bomb hit, then it was delete all the files off the device and drag and drop again. It's not an easy workaround, but right now it's the only smartphone platform that you can use. Although with WinMo 6.5 you should have the option to sync using the Zune Software.
(Where's Pink, Microsoft??? We really want a Zune phone. Really!!)