I have no confirmeation, but if you look at the annual report from last year, in the first few pages it mentions africa could be ready to open in feb 2010, brining 14 new exhibits to the zoo.
Not sure though, this is the only news that noone i know has heard of it. I honestly don't know what is next, but due to the carpark and ele facility opening in feb 09 or so, a years worth of construction might not do it. I say it may start after this, but will take maybe 18 months.
also taronga will be without many of it's favorites during this time, as all animals in that area will ahve to go to other facilities, propbably western plains, as there is simply no room to build and keep giraffe, zebs, ostrich, bongo, barb sheep etc. The chimp and gorrilla exhibits will also be included, so for a time, they could both be shut, and the main walking strip from rept house to food precint will also be shut, there-fore extending the wlaking track around zoo significantly for guests.