You know, I have to admit that the main reason academic researchers don't appreciate the sophisticated proof-of-work/proof-of-retrievability features in Tahoe-LAFS is that I didn't write it up. The 5-page paper that I linked to -- http://scholar.google.com/scholar?cites=7212771373747133487&... -- doesn't explicitly mention that it has proof-of-work/proof-of-retrievability properties at all, much less do the sort of thorough, precise specification and proof that, for example, the HAIL paper has.