The current concentration of effort in Europe on electronic signature standardisation. 

Note that this supercedes the previous EESSI program of work.  

To enable substantial cost savings and improved customer delivery, the US Patent & Trademark Office wanted to implement a single, highly scalable, and secure infrastructure that would support both internal and external applications.

The USPTO implemented an in-house PKI to authenticate attorneys lodging patent applications online.  The Return on Investment is one of the best documented cases in PKI, and is based very simply on savings related to elimination of paperwork.  

The Internet2 PKI Labs work to advance the
state of the art in network services for authentication and
authorization. The PKI Labs focus on interoperability and
manageability, trust and delegation models, and scaling in the
technical and human dimensions of PKI.

One of the most comprehensive PKI link farms, including probably every CA on the planet, plus an exhaustive list of legislation and technical standards.