If you just want a straight linux-based PMP, the Titan Omni is supposedly currently available.
http://www.linuxdevices.com/news/NS9400496044.htmlhttp://titan-entertainment.net/home_omni.html# 4.3-inch "HD quality" LCD
# 30GB hard drive
# Bluetooth wireless
# USB 2.0 interface
# Lithium ion battery offering 8 hours of video or 15 hours audio playback
# Weight -- 15.2 ounces (260 gm)
# Audio/video I/O supports MPEG4, DivX, XviD, WMA, MP3, OGG
# DVD recorder functionality
# Photo wallet functionality
I wonder if Sharp will ever figure out that by adding video out and a graphics co-processor that they could extend the market for the Z's.