I'm afraid you can't get away with doing nothing for italian in 2012, unless you have incredible natural ability, which is probably like 1% of victoria doing yr 12.
You need to have your grammar perfect, things like the subjunctive, correct use of irregular/ future/ other past participles etc. will be the things that get you A+s, especially in the orals, also revise on gender, for example you may forget e goes to i for plurals and singular e words like paese are sometimes masculine. I'd advise you to revise on grammar more than vocab for the holidays, i'd do:
* 60% grammar
* 20% listening
* 20% reading
You're first sac will probably be writing like I had, and as opposed to practicing writing on the holidays, you will know all the grammar (well, a lot of it) and can just start practicing writing once you start, like handing in pieces to your teacher for her to grade.