Nicholas Laughlin's blog etc.

Is it "Internet" or "internet"? Does the capitalisation matter? Joseph Turow thinks so.

I prefer "Internet" myself. Turow argues that "dropping the big I would sent a deeper message to the world: The revolution is over, and the Net won. It's part of everyone's life, and as common as air and water". But air & water are substances, belonging to a category of words not usually capitalised; while the Internet, though properly an abstraction, is metaphorically thought of as a place, & traditionally place names are granted a distinguishing initial capital. I suspect the cap-I will stick unless we significantly change this mental image.