Yea - I received an email in early Feb (c. 3 weeks back) asking me to apply for the JJ/WB program. It required submission of some other personal statements and references. As I was saying - the process is fairly opaque but I think it was HKS that nominated eligible applicants (did you fill in a survey that the MPA/ID program had emailed about in January)? You need to satisfy a set of criteria to be eligible (be from a developing country, at least 3 years of development work exp etc etc).