They discontinued it due to contractual issues with the manufacturer, BroadCom (iirc). However the idea behind that device still holds well. You can, for example, connect your laptop to the internet through ethernet and use the WiFi as an AccessPoint for your NDS to connect to (using Internet Connection Sharing). Or, if you can't use ethernet, you can get a certain type of WiFi dongle (I think it had to be reprogrammable, but I can't remember) to do the same thing.
I've got a Ninty USB WiFi, so I've never actually needed to use the above (and I can always change the secondary WiFi on my router to WEP for my NDS and PSP), although I have used the setup in reverse - connecting my Xbox 360 to my laptop through ethernet and used ICS on the WiFi to get internet on my Xbox.