I'm a little bit confused about the plugins.

Why is there a pixelpipe upload service and several services-plugins? Does that mean, when uploading on "pixelpipe" it will send pictures to everything set to default (except when using tags) and when using a service it will send it to that service only? Does that mean when uploading to yfrog for example, it uploads a picture to yfrog and sends a tweet? What is the "twitter service"? Where does it upload the pictures to? Does it also tweet?

I'm a bit confused.