Sometimes workers will want to share their calendaring application with an outside freelancer who won't have compatible software, Andrews said. "It would be handy to integrate everything with outside people. This is one of those cases where easy can trump power," he said.

"I think we'll see an uptake in this area," Andrews added. "Maybe it's not a realistic expectation for large enterprises to look to Google for e-mail, though."

What will make or break enterprise use of the upcoming premium Google Apps services, he said, are transparent, predictable service-level agreements for businesses.

"Their service has got to be kind of Apple-class -- you know what you're getting and you know it works," he said. "They need to have a good integration story about everything they've got, which is still building."

Maurene Grey, principal analyst at Grey Consulting Inc. in Kent Lakes, N.Y., said Google's biggest challenge in making this strategy work is in convincing business users that Google is also a business-focused company, in addition to its established history as a consumer-focused vendor.