Mystery plant - edible?

This is growing in a creek/stormwater drain just down the road from my house in the Perth hills, Western Australia. The creek has been dry all Summer (it's just coming into autumn).

I'm 99.9% sure this is an introduced plant, does anyone know what it is and/or if it's edible? The berries look inviting and I'll go pick them if they're safe to eat.

ETA : Well, it looks like I haven't found free fruity food. Consensus is that it's a nightshade of the deadly kind.

( Big pics under the cut )