The USB digital out function is not limited to Nokia phones. Android ICS apparently has this functionality as well, but Google hasn't properly implemented it yet:http://code.google.com/p/android/issues/detail?id=24614&sort=-stars&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars
Apparently, the guys at cynogen mod managed to get it to work on the Nook. It's not common place now, but soon it will. I'm gonna get a FiiO E17, but I'm not too inclined to get cables from off alibaba or ebay, since I'm using them for hi-def audio. So I'd strongly suggest FiiO to make a USB 2.0 Micro-b male to Mini-b male adapter cables, maybe with 90 degree connectors, or perhaps one that's coiled. (YES, both ends at 90 degrees with a coiled cable. PERFECT.)
Just my SGD$0.02.
I've been waiting years for ICS to come out and then for USB out to become enabled. Couldn't wait anymore and bought a Nokia. Enjoy the wait, should only be a year or two more.