Melb due to get ground radar later this year, and yes the radar referred to by an earlier post is for that. Syd is the only place in Oz that has ground radar, and since that needed replacing the powers that be decided to buy three, so Syd, Melb, Bn are all due to have that installed and operational sometime this year.
Some taxiways are being upgraded for the increased lighting requirements assoc with Cat III, hence some of the zig zag taxi instructions due to short term closures for that work to occur (aside from the permanent closure of part of Sierra for the Intl Term expansion and of course the inevitable stand off parking for the intl's on the busy days).
I think the black boxes at the threshold Rwy 16 are some kind of noise monitoring thing, i did get told but the info went into the oh, whatever file.