Firefly acts as a shared iTunes library. Firefly does indeed need a rescan, but the shared library is available to all computers on the network. So that way they all have the same music.
Also, you can set a ‘rescan interval’ to have firefly rescan every x seconds automatically. (up to minutes, hours days, etc)
So in that way, firefly will manage your music, and share it to any PC’s on the network.
Next to emulating a shared iTunes library, it can be approached in several ways.
Thus allowing other clients to access your music.
Fireflyclient is a java application; An alternative to iTunes, but allowing easier access than iTunes from outside of your local network. (Over the internet)
Fireplay is a flash-based web app that is hosted at the same spot as the administration page from firefly. When you open your browser to Fireplay, a webbased flash client is viewed, allowing you to stream music from firefly to the PC with the browser.
Hope this clarifies a few misunderstandings…