Ahh, the magic of the web!
Your laptop is working as a webserver, and any browser on it's network can make requests of the server. Laptop, HandheldPC, squeezebox, softsqueeze, cellphone, anything with a web browser. If you make your slimserver available to the internet (not advised) you could play songs from anywhere, except you couldn't hear them
Wait til you discover the skins and plugins like Inguz.
Lots of fun.