Optus has lined up alongside AAPT, Exetel and TPG in offering an "unlimited" broadband package. As with its rivals, the devil is in the detail -- "unlimited" in this case is code for "we'll shape you after you exceed the limit".
In our recent discussion of why ISPs don't like unlimited plans, we noted that those ISPs which do offer the option generally reckon on most people not utilising the option. Optus' Fusion packages make sure of that -- while the package is promoted in its media release as "unlimited broadband which can be used at any time of the day", in practice you'll be shaped once you hit the limit (15GB on the $99 package, or 50GB on the $129 bundle). That's probably enough for many people, but I don't think it's what most people mean by "unlimited".
Other changes on Optus' offerings include a $10 drop in its entry-level Naked DSL plan, and the elimination of excess usage charges (in favour of shaping once again) on most packages.