The easiest way to describe Shozu is to compare it to PageOnce. Shozu is essentially the social networking/photo only version of PageOnce. Now that doesn't mean in any way that they're made by the same people. It simply means that they operate in much the same fashion.
Shozu requires you to log in and make an account with them. Then it provides you with a list of different services (and there are MANY) that you can have it synch up with. All the services will allow you to upload a photo directly to that service, and depending on what service you're using, you can also update your status (like with Twitter or Facebook for example).
But Shozu doesn't just allow you to push out this information, it actually allows you to get some feeds as well. So instead of loading up the Facebook app and Twitterrific to see what you're friends are doing, you can easily just load up Shozu and see all the updates coming in at once.
If you're worried about privacy or the fact that everything is in one place, take a deep breath and just remember that this is all just social networking and photography junk. If that still doesn't calm you down, Shozu has also enabled a delete all button that will purge it of its connections with all of the different services you've let it pair up with. If you find yourself using multiple social networking services and constantly uploading photos from your iPhone, then Shozu is a no brainer.