Official line here: http://www.customs.gov.hk/eng/advice_advice_e.html

Any amount of anything under 30% alcohol is now OK.

Interestingly, I just priced some wine at Changi for the first time, thinking I might bring a few bottles back. The duty free price of a wine I know was actually 10% higher at Changi than the pre-budget supermarket (not duty free) price in Hong Kong. So on that basis I ain't going to be buying any wine at SIN!