The official hotel is Hyatt Shatin, Hong Kong (just next to the conference venue) . You can book the hotel online here.

Other nearby hotels (within a few MTR stations) include:
Royal Park Hotel . The booking form is here.
Regal Riverside Hotel . The booking form is here.
Courtyard by Marriott . The booking form is here.

More information about these hotels can be found here. Note that the rates provided by these hotels may not be cheaper than the rates provided by other agents as the hotels may provide more flexible booking options.

Hong Kong is a small city and the transportation system is one of the best in the world. Basically, you can stay in anywhere in Hong Kong and can get to the cconference venue within an hour using public transportation. Here are more options for the hotel (links provided by Hong Kong Tourism Board):
Other accommdation options and a searchable interface.