Apparently, the new service has been unveiled by accident, due to a blunder of Yahoo’s PR department. Invitations to join were delivered to the wrong people while the new service was in alpha phase and now Yahoo had to come up and makes things clear.

Then again, the so-called blunder got everyone talking about Mash. It got Yahoo better coverage and potential users more interested, so don’t bet everything on the “accident” theory.

Up till now only a handful of details have been revealed about Mash. In a first (and only) post on the Mash official blog, developer Will Aldrich talks a little about what makes Mash different from rivals such as Facebook or MySpace. There are three things worth noticing, he says:

“1.You can make starter profiles for your friends. Think: “first round’s on me.”
2.You can leave your profile open to contributions by trusted friends.
3.You can customize your — or your friend’s — profile with modules from a growing gallery of apps.”

Aldrich also mentions that the service features “extensive privacy controls[…] and you set the boundaries that you’re comfortable with,” as well as the ever present bugs and that more features are on their way.

There has been no word whether Yahoo 360 is to be closed or not. Our bet is that 360 users will eventually get an offer to move over on Mash, if the new attempt gets off on the right foot.