Nintendo have made Wireless gaming great with their Wi-Fi connection. It makes playing games online fantastic. I have just bought a Nintendo DS-Lite, along with Mario Kart DS, Need For Speed Carbon - Own The City and Ashphalt Urban GT 2. Playing Mario Kart over the internet is great fun, as you never know who you are playing with, unless you use the friend code system, which enables you to play against your friends online.
What is also good about the system is that Opera have made a browser for the Nintendo DS, so that you can go online on the DS, either through your home wireless network or at a free Wi-Fi hotspot, thus making online gaming fantastic.
The Wi-Fi connection is also available on the Wii, although there is only one title available at present - Mario Strikers Charged Football. Hopefully more titles will be available for online play, as it would be silly not to make them online compatible.
Another benefit of the Nintendo system is that the service is free, unlike some other console online services such as Xbox Live, or Games For Windows Live, which charge you to play games online.
All in all Nintendo have created a winner, and with the right games then Wi-Fi connection will become the best online gaming experience.