Basic information about the Wallaby is at: http://wiki.xda-developers.com/uploads/tmobile-pocketpc.pdf
Hardware aspects of the Wallaby and Himilaya are not divulged by manufacturer HTC. Therefore it needs painstaking reverse engineering to discover how they work. Interesting information can be discovered in the bootloader. Especially the Wallaby bootloader contains a lot of information due to the diagnostic software it contains. Currently parts of the bootloader are reverse engineered using IDAPro.
Some information regarding the Wallaby: