On a recent flight from SIN, we were allowed to land in SYD just after 5am.
Even with that dispensation, we still circled around and did nothing for quite a few minutes until actually starting the approach at 5am. I think we touched down at 5:10am.
We landed from the ocean, and took a really long path to the approach (I get a feeling we were high up over one of the National Parks, then headed out to the sea, and back in). Someone might be able to help me name the national park !
I saw at least one other plane doing a similar circuit, and another big jet had just landed in front of us, so we weren't the only ones with that dispensation.
I've also been on flights where they've circled, umm'd and aah'd over the landing due to the curfew. There are pretty big fines if they break the curfew without an exemption!
I don't know if I agree with flight curfews at Airports or not. My thoughts are not really relevant for this thread, but it is still something I havn't made a decision on.