If you would like to pick some berries and didn't get to the Gnomes' Home that Andrew wrote about, there are a couple of websites that you should consult so you can pick your own before Christmas.
Cherries South Australia has a list of lots of local cherry orchards, their openning times, contact details and a map.
This coming weekend starts the season for blueberry picking at The Blueberry Patch at Mt. Compass. The damp, boggy land, in the middle of dairy country was seen as a waste land, until these people bought it and turned it into a beautiful blueberry patch, the likes of which I have never seen anywhere else in South Australia.
I went there with friends Kathy and Ken in December 2007, and wrote about it here. We picked 30kgs in 1 hour! They freeze beautifully so long as you don't wash them first. I just put them into 500gr yoghurt containers and put them in the freezer. They came out as good as the day I put them in.