Marcus Ranum and Bruce Schneier recently had another one of their "face-offs," this time, discussing anonymity on the Internet
. Bruce argued strongly in favor of it, but then so did Marcus - with a cleverly nuanced argument.
The problem with Internet anonymity is that it's so incredibly cheap - fraud and spam is easy to do because it's almost free to adopt a new identity on the Internet. Many spam/scam techniques rely on creating bogus IDs wholesale.