At companies across the country, employees are being fired for Internet postings employers do not like. It is a new and increasingly prevalent cause for termination. The firings raise a central question: How much anonymity can anyone expect on a portal called the "World Wide" Web?" Many people don't understand how what they're writing on a blog is not as anonymous as they think it is," said Kurt Opsahl, a staff attorney for the Electronic Frontier Foundation, a nonprofit advocacy group. "They feel like they're having a conversation with friends and family, when they're really having a conversation with anyone who comes by."