Monsignor Guido Marini is currently the Master of Pontifical Liturgical Celebrations. He replaced Piero Marini (no, they're not related) in this capacity as of October 1, 2007.
The previous liturgical master was known for ceremonial that is more "contemporary" and "cultural". Guido is known to be more traditional and in line with the preferences of Pope Benedict XVI.
Interestingly enough, Guido Marini received his doctorate in the psychology of communication.