Today MySpace launched its Brazilian Portuguese website with the goal of challenging Google’s Orkut, which is favored by 14 million of the 20 million Brazilian active internet users. The English version of MySpace already has 1 million samba lovers. But they might be late to the dance. Other social networking tools have already taken hold over there.

Regina Bustamante, Director of Globalization at Plaxo, tells us that her number one foreign language is Portuguese, because of the widespread use of the contact sharing tool in Brazil. Since it launched Pulse (Plaxo’s social networking platform), Plaxo has seen the number of users in the Netherlands spike every month (with no localized version). On the business networking side of the ledger, LinkedIn has around 16 million users with no localized version (unless you count English for the social-networking-obsessed U.K., where the company claims 1 million members), growing at about 1 million users per month. It biggest competitor is XING in 16 languages.

Here is where the social networking phenomenon represents an interesting challenge for localization: It is driven by the community and not by business cases. It grows by word of mouth regardless of translation. Social networking is local and in the local language. More important than the tool or the environment is the adoption by people who have the power to produce social epidemics, as Malcolm Gladwell described it in The Tipping Point: connectors, mavens, and salesmen. Of course, there are other, more adult directions in social networking that involve one of the biggest drivers of traffic on the web — but that’s another story.