Users of the popular Gmail service could be open to an attack via Wi-Fi according to claims by a security researcher.

Robert Graham, CEO of Errata Security says that because of the way that the Google handles secure SSL connections. When a user connects to Gmail it starts off using a secure SSL (HTTPS) connection, but if for some reason it fails then Gmail will resort to sending unencrypted data.
The claim is that an attacker can extract an unencrypted session ID which will allow them to again access to the account.

But if you use a free public email service for your highly sensitive data then what would you expect?