Quick and easy file sharing is hard to do not only from a technical standpoint, but also from a legal standpoint. It only takes one DMCA lawsuit to shut down a file sharing startup. The likelihood of a lawsuit increases as the file sharing becomes easier, quicker, and more anonymous (as the chances that someone will use it for illegal purposes increases the easier and quicker and more anonymous it becomes).
You have to set some restrictions on who can share what with how many people and how often. Even torrent trackers that do not store any files other than the tracker become targets. I really would love it if there was a way to type "scp /home/freehunter/your-granddaughter-laughing.mpg //grandma/home/grandma/videos" with UPnP to get around grandma's dial-up NAT. Unfortunately, the closest we have is Dropbox (requires an account) or BitTorrent (requires dodging law enforcement and porn popups).
You have to set some restrictions on who can share what with how many people and how often. Even torrent trackers that do not store any files other than the tracker become targets. I really would love it if there was a way to type "scp /home/freehunter/your-granddaughter-laughing.mpg //grandma/home/grandma/videos" with UPnP to get around grandma's dial-up NAT. Unfortunately, the closest we have is Dropbox (requires an account) or BitTorrent (requires dodging law enforcement and porn popups).