During its press conference to announce it would give free cases to iPhone 4 owners to help deal with the phone's reception issues, Apple also talked about release plans for the phone internationally. Australia was included on a slide with July 30 as the release date.
Apple Australia hasn't yet issued a press release confirming that information, so we still don't have any price details. Earlier this week, I wrote that it was unlikely the phone will appear in July, but Apple now looks to be (just) making that deadline. What past history does suggest is that we won't see any information on price plans for the new phone until around July 24.