The American Bar Association has a formal statement on the matter:
2. J.D. Degree - Ph.D. Degree Equivalency.
WHEREAS, the acquisition of a Doctor of Jurisprudence degree requires from 84 to 90 semester hours of post baccalaureate study and the Doctor of Philosophy degree usually requires 60 semester hours of post baccalaureate study along with the writing of a dissertation, the two degrees shall be considered as equivalent degrees for educational employment purposes;
THEREFORE, BE IT RESOLVED, that all appropriate persons be requested to eliminate any policy, or practice, existing within their jurisdiction which disparages legal education or promotes discriminatory employment practices against J.D. degree-holders who hold academic appointment in education institutions.
I suspect that as the number of those holding LL.B.'s dwindle, the usage might eventually come into fashion. Someone graduating in the last couple of years told me that all letters sent to alumni are addressed with the 'correct' title.
So, here's my proposition: let's use the proper title. Always. Starting today, call all your local J.D.'s by their proper title, and let's give them their due!