Definition:
A hacker prevents access to an authorized Wi-Fi access point and re-directs a mobile professional to a false access point where information or access to networks can be obtained by the unauthorized person.
The unauthorized user can also gain access to VPN client software. The unauthozied user has created a twin of the real access point yet because it is not the true access point, it is referred to as "evil".
The seriousness of this as a true threat to mobile professionals is still being debated, there are those who feel it is too cumbersome and too obvious a method to gain access to data.
Examples: Mobile professionals should always employ security precautions in order to prevent themselves from being vulnerable to the Evil Twin Threat.