Facebook Messaging adds email, IM and SMS to Facebook messages. Some portion of the social network’s 600+ million users will switch to Facebook for an all in one text-based communications service
Switchers to Facebook Messaging in the US will reduce the display ad revenues of traditional portals, like Yahoo! and Microsoft, which use such tools to drive traffic
Less affected is Google. Some Gmail users will switch, but Google’s core business model is selling search advertising, where it is not challenged by Facebook (yet)