Anonymous networks doesn't really help if you are liable for traffic passing through you, like with recent actions against ISPs. I think the future is trust-based networks like friend-to-friend. When broadband speed averages increases, it will become feasible to relay traffic through trusted peers.
Doesn't putting tor underneath suffice?
Tor has well known issues with the Bit Torrent protocol, tangentially there was a well known exploit where someone running a Tor exit node ended up capturing all to and fro traffic.
No, don't do that. If you want well-working and most appreciated filesharing on an anonymous network, please join us I2P fans: http://www.i2p2.de