Just bought the SheevaPlug development kit from Globalscale. Will start working on putting DZ3 on it as soon as it arrives (estimate wait is 2-3 weeks).
Feedback from people that have used this device indicates that it is not really usable without external hard drive (either network mount or external USB), you may want to keep that in mind if you decide to follow suit.
On the other hand, changes that are planned for DZ will make disk unnecessary, so you may want to hold that off if running DZ is the only thing you are planning to buy this device for.
Bonus feature for external USB drive would be to find an enclosure that is able to report the disk temperature via smartctl or hddtemp - if you find one, please let me know.