"These are natural growing pains for an on-demand vendor," she said. "Google is doing what it needed to do [to respond to the outages], but in fairness to Google, it's held to a higher standard in terms of uptime and availability, as are many on-demand vendors, when you compare them to internally deployed applications."
Apps comes in various versions, including the free Basic and Education editions and the fee-based Premier edition. In addition to Gmail, it includes Google hosted services like Calendar, Sites, Talk and the Docs word processor, spreadsheet and presentation software.
Overall, more than 500,000 businesses with 10 million active users use Apps. Hundreds of thousands of those active users have Premier subscriptions, according to Google.
With Apps, a hosted suite of communications and collaboration applications, Google is a leading proponent of SaaS (software-as-a-service), an emerging model of software delivery that backers say represents the future.
Because vendors host applications in their own data centers, companies don't have to concern themselves with hardware provisioning and software maintenance. By living in the Internet "cloud," these hosted applications simplify sharing and collaboration among employees.
However, outages such as the one Gmail experienced are among the biggest question marks regarding SaaS applications, as IT and business managers ponder whether to ditch conventional software packages that are installed on their companies' servers.
When applications hosted by vendors go down, there is little that IT and business managers can do to remedy the situation and respond to their angry end-users.
Google Apps critics question whether the suite can really provide enterprise-grade software availability and performance and thus be a real option in large companies to conventional, on-premise options like Microsoft's Office and Outlook/Exchange or IBM Lotus Notes/Domino.
Google acknowledges that most Apps subscribers are individuals or small and medium-size organizations. However, the company has high hopes that the Premier edition, with its IT management and enterprise software integration features, will push into the enterprise market of large companies.
Google has proved it can learn from mistakes and has improved as an enterprise IT provider, Cain said. However, Gartner's advice to enterprises is to hold off on adopting Gmail as an e-mail system, and this month's outages justify that position, Cain said.
"A 24-hour outage of e-mail for many companies would be catastrophic. That indicates that our cautious approach is warranted," he said.
Before giving the green light to its customers, Gartner wants to see at least a dozen enterprise deployments of Apps Premier with at least 10,000 Gmail seats, each running successfully for six to 12 months, Cain said.