Why under 40? Sometimes older woman jump in after 40! I really like Tracey Reichow of Black Cat Vineyard. She fell in love with wine after working in investment banking. So even though she doesn't fit the age profile, she is still relatively new to winemaking. However, her wines have a definate old world style and maturity that can only come with wordly experience!
Just 3 right now from VisitVineyards.com in Australia:
Geraldine McFaul - Willow Creek, Victoria
Helen McCarthy - Taylor's Wines, South Australia
Fran Austin - Bay of Fires, Tasmania