Yes, yes it definitely is. You'll see many public parks with signs up warning about swooping magpies. Little kids attach ziplock ties or pipe cleaners vertically to their bike helmets to try to discourage maggies coming at their heads. If reported to the council, serious cases will be relocated to nearby bushland, but they often come back to their original territory. I've never been attacked more than a little warning swoop, but I've watched many kids getting harassed on the way to school.
When my husband first moved here and saw those helmets, he thought they must have all been special ed kids or something.