The licensing appears fairly permissive, however is only free as in beer, not free as in speech. There are no direct restrictions preventing use of the assemblies in GPL works however.
Currently, the SDK is only released through Konica Minolta Europe's Developer Support Program, and according to the sign-up page, you shouldn't access it if you live outside of Europe (however, with most non-obvious email addresses, who knows where you are?). Additionally, the registration form requires a company name, so it is expected you at least work somewhere...
The Developer Support Program also includes specification documents for other developer related topics unrelated to this SDK specifically such as PDL and MIB specifications.
The Developer Support Program is free to sign-up, however for direct support from Konica Minolta, a charged subscription is required (there's a moderated discussion forum for non-paying users though)
Ever wanted the Konica Minolta MFP in your office to do exactly what you tell it? Here's your chance!"