For the question of Fred Astren regarding the antique/medieval rabbinic and academic scholarly treatments of tekhelet:
For Basic maetrials which were indeed the beginning of this modern discussion see: R. Gershon Leiner, Maamar Ein Hatekhelet; idem., Ein haTekhelet; idem., Sefunei Temunei Hol.
R. Menachem Borenstein, Hatekelet, Jerusalem 1990.
For the current controversy see:
1. Mitzvat HaTekhelet biZemanenu, Jerusalem 2010, who claims that the original Tekhelet is made from a distinct species of shellfish called purpura pelagia.