Mash is different from other social networks in that you can start profiles for your friends and "open" your own profile to friends you trust, according to the Mash blog. What that means, exactly, is still a bit unclear. You can also reportedly customize your profile or friends' profiles with other apps, ala Facebook.
"One last note before you jump in: Mash is still pretty raw--there are bugs and we haven't gotten to several of the features it really should have. We need to hear from you about where to focus our efforts," writes Will Aldrich, the head of Mash.
Do we really need yet another social networking site? If you are in love with all things Yahoo!, perhaps, since it integrates with Flickr and Yahoo! Mail, but does anyone really think this will attract users away from Facebook and MySpace?