Buzzy stealthy startup Path, which was founded by ex-Facebooker Dave Morin and Shawn Fanning, finally launched its mobile app tonight. It is a private photo sharing iPhone app similar to Instagram or PicPlz, except that it makes sharing photos more difficult than it needs to be.

Path is designed to share photos with only your closest 50 friends, primarily through the app itself. You can&'t Tweet out links to your photos or share them on Facebook. It is very much for personal photos and private moments, the kind of pictures you share with family and very close friends. The problem with Path is that for many people, those family members or friends don&'t necessarily have an iPhone. They can still see the pictures on the Web, but you really need the app to place photos back into other people&'s streams.

In other words, the Shutterfly network (the people with whom you share your wedding and vacation photos) are probably not going to be using this app. Instead you are going to find the same people you share things with on Twitter and elsewhere. This is already happening to me in the hour or so since I&'ve downloaded the app.

I am going to make another prediction. The types of photos people are going to share on Path by and large are going to be the same as the photos you see already in more public photo-sharing apps: meals, drinks, friends, kids, cats, dogs, and the random dross of daily life. Knowing that it is &''private&'' and &''safe&'' is not going to change much of anything.

There are times, of course, when you don&'t want to share a photo widely with the world. But those are the exceptions. A better privacy model would be to make photos public by default and allow for a private mode with certain photos to be shared only with select individuals or a core inner circle. Public sharing allows for more serendipitous connections. But then Path would be just like every other mobile photo-sharing app. I&'ll give it credit for going its own way.

Path doesn&'t seem interested in making anything other than visual connections. You can&'t even comment on someone else&'s photo. It is oddly passive for a social app. You put up photos, see other people&'s photos, and that&'s it. No discussion allowed.