Last Saturday, 29th May 2010, Starhub and M1 begun selling MicroSIM cards and SingTel will follow behind on 1st June 2010 which is tomorrow.
No idea whether does the telecos here allow MultiSIM card to have MicroSIM or it is strictly for data plans only. Nevertheless, you still can cut it to MicroSIM size by using just a scissors. Just BECAREFUL not to even snip a bit off the golden metal contact point as it will make the SIM card useless.
It seems that SingTel have already begun preparing MicroSIM for users. Accordingly to the user “MorpheusV” who posted in this thread, Looks like SingTel has started saling MicroSIM, states that when he sign up for SingTel’s 7.2Mbps 2 years contract, it comes with a Huawei E5832 and the sales person told him that the SIM card of the plan would be MicroSIM.