Sources: The Hindu Endowments Board (Singapore) and Singapore public holidays. We have learned through private communications with one of our Singapore contacts, that the Hindu Endowments Board has revised the date for Singapore's 2008 Deepavali public holiday, from Tuesday, October 28, to Monday, October 27.
Such same-year adjustments to the announced date of Deepavali in Singapore have happened in the past (in 2002 and 2003, for example). Note that the 2008 public holidays page of the official website of Singapore's MOM (Ministry of Manpower) has not yet been updated to reflect the above-mentioned change.