The EGS 2004 event, open to the public, runs though today.
If you live near Mexico City, you can play Nintendo DS today and even win the system for yourself. The Electronic Games Show (EGS) 2004 started Friday and ends today at the World Trade Center Mexico. The event is open to the public with admission around 80 pesos ($7 USD). Not only does Nintendo have playable Nintendo DS systems, open to the public for the first time in North America, but they are giving away Nintendo DS t-shirts. There is also a Donkey Konga tournament, and the winners will receive a Nintendo DS system! Other contest prizes include games signed by Shigeru Miyamoto. Go to the link above for more information (the event website is in Spanish).
Thanks to Nicolas and Karancho for the info!