Via Overlawyered, news.com.au is reporting that the Vegemite ban may be a hoax:
Supermarkets in the US continue to stock Vegemite and say they have no plans to remove Australia’s iconic savoury spread from their shelves.[...]
But weekend media reports said US customs officers had been taking jars of Vegemite from travellers’ bags as they entered the country.
“We are aware of reports that US authorities have been seeking to stop people from bringing Vegemite into the country,” a spokesperson from the Australian embassy in Washington DC said.