I sat in on a presentation by Perth Airport recently showing their plans to further develop the internatiional side. It all looks pretty impressive with the nice computer graphics but without a parallel 03 / 21 it probably isn't going to achieve much to relieve the congestion during the morning peak departure times. There are plans afoot for the extra runway but as Griffo said, don't hold your breath. There will be quite a bit of lease resumption required along the light industrial strip between T1 and Tonkin hwy to make that happen.
Also planned are hwy flyovers for the Horrie Miller dve and Leach hwy intersections on Tonkin hwy which hopefully will aleviate that painfull bottleneck that occurs both ways along there every morning and afternoon.
I had a box load of their big glossy bruchures but promptly put them in the bin. There is also some information on their
website