Mobipocket has said it will release a Linux version of mobigen.exe, but it is not a high-priority project.
joblack, why do you think mobigen.exe could not be analyzed to crack the DRM? Mobipocket will probably not release the Linux version as Open Source. It should be as hard as cracking the Windows version.
In itself the DRM cannot be that complicated. The mobigen.exe options talk about vouchers and from the PID we can deduce that it is mainly an encryption with the PID.