Mexico City. Global Million Marijuana March (GMM-MMM). Partial archive for 2006 media coverage.  Google News does not index all the media. This page is mirrored at these locations just below. If one isn't working right, then try the other:
http://www.angelfire.com/rnb/y/e/mexicocity2006mmm.htm
http://corporatism.tripod.com/e/mexicocity2006mmm.htm

Google News was used to find most of the results. It does not index all the media. 
There are some Yahoo News search results at the very end. There are many more media sources not indexed by either search engine.

Google News results archive farther down for this search shortcut:
http://news.google.com/news?q=marijuana+%22mexico+city%22+smoke-in&scoring=d

Vetoed drug bill sparks Mexican smoke-in protest CTV.ca, Canada - May 7, 2006 ... About 500 protesters held a marijuana smoke-in Saturday at a park in downtown Mexico City, where youths openly smoked joints and a heavy odour of marijuana ...

• Pot smoke-in held after Fox doesn't sign drug bill
  Fort Worth Star-Telegram - May 09 8:32 AM
  Six police officers quickly retreat after protesters surround them and shout "Take us all, take us all!"
• POT OF BOTHER
  Daily Record - May 08 1:48 AM
  About 500 cannabis-smoking protesters have held a smoke-in in Mexico City. They're angry president Vicente Fox refused to sign a Bill that would have made possession legal.

• Vetoed drug bill sparks marijuana smoke-in, becomes political issue in Mexico
  CNews - May 06 8:40 PM
  MEXICO CITY (AP) - Marijuana-puffing protesters - backed by a candidate in July's presidential election - held a smoke-in on the streets of Mexico's capital to show their support for a bill that would have eliminated criminal penalties for possession of small amounts of drugs.