
For that scenario, the author's approach to multiboot seems similar to SheevaPlug makers: one SD Card per OS with Uboot and specific boot scripts. A multipartition USB Thumb stores rootfs for each OS. Its similar to Install OS using 2 partitions approach. The difference is, Uboot here allows to select SD Card configured OS at boot time, otherwise default OS is started. Selection is done via a serial console or netconsole running on your PC.
I wonder if its possible to place Uboot files on the 1st partition of the same USB disk instead of SD Card, and move specific boot scripts to each OS partition, or choose a boot script at boot time from several stored on 1st partition. Since Dockstar and Pogo devices offer 4 USB ports and no SD Card port, this needs adaptation, unless external USB Card Reader is used with Dockstar.