Upgrade in Australia?

Amy, I bought my streak in Australia through Optus network. However, the phone was not locked to Optus network and I'm using 3 mobile sim card now. I tried Froyo upgrade through 'settings->About device->System updates' but got a message that no update is currently available. Do you know when froyo upgrade will be available in Australia? Or is there another way to upgrade to Froyo? Look forward to your reply.

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