Microsoft spent $1.2 billion in 2012 to buy ESN vendor Yammer in order to boost the ESN features of SharePoint, Office 365, and several other of its business software products.
"Microsoft has declared that Yammer will be the center of the Office productivity experience -- early moves include Yammer feeds as part of SharePoint -- so Google needed a comparable capability for Drive," said Forrester Research analyst TJ Keitt via email.
"I don't know if this is the thing that gives Google Apps an ESN story," Keitt said. "But I've argued that what would be really interesting is combining Drive with Google+ so that content is an active participant in a circle."
Pure-play ESN vendors include Jive Software and NewsGator, while some larger vendors have their own ESN products, including Tibco (Tibbr), IBM (Connections), Cisco (WebEx Social), and Salesforce.com (Chatter.)
Juan Carlos Perez covers enterprise communication/collaboration suites, operating systems, browsers and general technology breaking news for The IDG News Service. Follow Juan on Twitter at @JuanCPerezIDG.