Putting an end to all the speculation, Yahoo! has started testing its own social networking site, called Mash, in a bid to lure users away from rivals Facebook and MySpace.

The company on Friday said it started inviting selected people outside the company to try out the new site, which some are calling “the Wikipedia version of a social network” where users can start profiles for their friends and “open” their own profile to contributions by trusted friends. Other than that, the service includes features similar to those found on Facebook and MySpace. Particularly, it seems that Mash will be following in Facebook’s footsteps by opening up their module development platform to 3rd party developers – something that has proved very successful to the popular social networking site.

Yahoo has struggled to compete in social networking, a business whose online advertising market is expected to reach $2.5 billion by 2011. The company's previous foray, Yahoo 360, has failed to gain much ground, while rivals MySpace and Facebook continue to gain users.