If you intend to use the iPad in Hong Kong, you can get this new microSIM card. It comes as a SIM and MicroSIM. Depending on what device you intend to use your SIM card with, just tear on the dotted lines. So far they do not provide an adaptor to convert a microSIM back to normal SIM.
I do have micro-SIM adapter at Vinko’s Treasures to convert them back to mini-SIM.
Although, this will only be useful for people who intend to share one mobile tariff plan with their pre-iPhone 4 and iPad.