Major publishers have joined the legal challenge to the Google Print service, arguing that it represents wanton copyright infringement. This as another battle in the ongoing conflict over intellectual property in the digital world, but I’m concerned it suggests something else: a challenge to the stability of the Internet as we know it.The Net works because of a series of informal agreements. Root server operators voluntarily point to the right places to make the domain name system function. Backbone networks “peer” to carry each other’s traffic without charge. And websites allow search engines to copy their content into indexes, even though at some level that action raises copyright concerns.The Google Print lawsuit puts the last of these practices in question. On some level, copying a Web page to facilitate searching isn’t all that different from copying a book to facilitate searching. And copying an RSS feed to put content onto another site isn’t so different either. Unravel the notion that some content sharing benefits everyone, and therefore should be acceptable despite the nominal boundaries of intellectual property, and the Internet economy, especially the Web 2.0 economy, comes crashing down.What’s worrisome to me is that, just as the informal practices for sharing online content are being challenged, the informal practices for sharing Internet traffic and addressing are under stress as well. Backbone carriers Level 3 and Cogent are fighting about who gets to peer, as SBC and Verizon — telcos with a very different culture than most Internet companies — prepare to take control of two of the largest Internet backbones. And the whole system of domain name management is in play as well, thanks to the UN’s efforts to establish a new governance structure.Years from now, will we look back at this as the period when the Internet came apart at its seams?