Laplante says he has one customer -- a small manufacturer whose core business application was built on WorkXpress and running on Amazon -- who has been knocked offline. "They are fired up and they are very angry," he said. The customer now wants the app hosted on a server in their shop.

Laplante said the Amazon outage, which began Thursday morning, is going to make it difficult to sell cloud approaches. "I'm going to have to sell against this outage."

For some, the Amazon outage may reinforce beliefs that cloud services aren't ready for businesses.

"We don't use Amazon or any other public cloud services and we won't, perhaps ever, or at least until there is much more transparency about where the data lives, who controls where it lives and when/where it moves, and lots of other things," said Jay Leader, the senior vice president and CIO of iRobot, whose products include the Roomba vacuum cleaner. Amazon's outage "just highlights why these are issues - just try to ask them what happened and what the impact was on your data, and even if they tell you, how do you know it's true and/or accurate?"

Paul Haugan, CTO of Lynnwood, Wash., said his city has been looking at Amazon's cloud offerings, but "the recent outage confirmed, for us, that cloud services are not yet ready for prime time."