I say "bubble tea" or "珍珠奶茶 (zhen1 zhu1 nai3 cha2)". The term "bubble" does not represent what it's made of but its appearance in shape.
And yes, it's originally from Taiwan and has now become so famous here and there, which kind of surprises me!
"Pearl (珍珠) milk tea (奶茶)" is a more direct translation of it though. Is it (usually) said so in Australia instead?