In Singapore, M1 and StarHub have already launched their prepaid mobile broadband whereas SingTel has yet to do so.
StarHub's MaxMobile Prepaid offering is more flexible than M1. If you've a mobile broadband modem, you can get the SIM card for $12. If not, you can pay $99 for Huawei E1550 2Mbps USB stick modem or $149 for Huawei E1750 7.2Mbps USB stick modem. User can choose the download speed between 2Mbps or 7.2Mbps and activate their plan for 1 hour, 1 day, 3 days or 5 consecutive days. The prepaid SIM card can be topped anytime and the balance is valid for 6 months. A fair usage policy of 2GB (daily) is being set for all data plans. Upon reaching the limit, a SMS alert will be sent to your MaxMobile Prepaid number. I've tested the 2Mbps service with Huawei E220 modem and it works well. The setting for APN is shppd.
M1 Prepaid Broadband costs $18 for 3 consecutive days with download speed of up to 7.2Mbps. If you don't have a mobile broadband modem, you can buy a prepaid broadband kit (SIM card + USB stick) at $128. You need to top-up within 90 days. The setting for APN is prepaidbb.