I've seen similar with some variations, not sure how dependable they are as some of them are unknown "china" brands..
One is the latest attempt by PCCW wifi + mobile broadband device, it's about half the size of your standard slice of pound cake and all you need to do is insert the provided SIM and off you go, can connect up to 4or5 WIFI devices.
There are others that mimic your broadband plans mobile device (PCCW Anywhere, Smarttone Vodafone, One2Free's NextG, etc..), same topology, just insert the SIM and you basically have a mobile hotspot, best bet to search for them in probably sham shui po.
I am not sure about other providers as I use One2Free/CSL and basically they have confirmed that any mobile device, be it a phone or mobile modem, if it supports HSDPA/3G, plug it in and go.
you have to be careful as some people have been caught off guard using the SIM in another device and was charged separately, I basically walked into CSL and showed them my blackberry, asked if I used the NextG SIM inside and use it just to surf internet, will I be charged other then my standard monthly rate.. better safe then sorry