A group of friends had flight itinerary HKG-SIN-MNL, with 5 days to spend in SIN at prepaid hotel. 2 of them were denied boarding in HKG because they were travelling on same PNR and the man had only 5.5 months before expiry date. This happened 2 weeks ago, on Jan 3rd 2010.
Maybe 2 days will be waived if proof of hotel booking and stars aligning right, but for sure they do not bend the rule for 2 weeks.