WordNet (r) 3.0 (2006):

up on
    adj 1: being up to particular standard or level especially in
           being up to date in knowledge; "kept abreast of the
           latest developments"; "constant revision keeps the book
           au courant"; "always au fait on the latest events"; "up
           on the news" [syn: abreast(p), au courant, au fait,
           up on(p)]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "up on":
   abreast of, acquainted with, adept in, at home in, at home with,
   au courant, briefed, conversant with, educated, enlightened,
   expert at, familiar with, good at, handy at, informed, informed in,
   instructed, intimate with, master of, posted, primed,
   proficient in, schooled, skilled in, strong in, taught, trained,
   up-to-date, versed, versed in, well up on, well-read in,
   well-versed