<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by rkkwan:
These private shuttles do not take the Octopus cards. You need to pay at the ticket counters directly. The Octopus cards only work with the Airport buses, or Airport Express. Can't use them on taxis either, unless things have changed.</font>
I heard they are working on getting the taxis to take the Octopus card but they were not set up to do so as of two weeks ago.
FlyerGold - the Octopus card is essentially a debit card that you put money on and use to pay your public transportation needs (tram, ferry, bus). The airport shuttles you're using are privately run so they are not included.
Enjoy your trip, HK is a wonderful city.