I now routinely carry a "travel pack" of Vegemite - it is in a sqeezable tube, 145 grams worth - with me when I go OS in my carry-on luggage. No problems with QF, I get some weird looks with other carriers though.
Sometimes gets confiscated by Quarantine when I get back, as it is a food product entering the country - the fact that it originated in Australia is irrelevant.
Funniest ad I ever saw was when NW started flying into Australia, and the ad showed that they were teaching their staff everything they needed to know about us.
One guy with a Yank accent held up a jar of Vegemite, and said "They won't actually make us eat this, will they?"
Quite funny, but you had to be there.
Dave