downtimeSalesforce.com is one of the big evangelists for online software and cloud computing, and its co-founder Parker Harris said today the company is working to address a major concern with the cloud: Downtime.

Obviously, web users don’t like downtime — witness the uproar whenever Gmail or Twitter goes down. And things are even worse when it affects your business, not just your ability to tweet what your had for lunch. Salesforce says it already provides more than 99.99 percent uptime for its web-based business applications, but it still can’t avoid scheduled downtime, when it has to perform maintenance or upgrades. Customers get advance warning, but it still leads to a few complaints, particularly when the schedule that’s convenient for Salesforce isn’t convenient for you.

Now, Harris said Salesforce is testing a program that would give customers access to their applications even when Salesforce is upgrading its service. Initially, you’d only be able to view the applications, not interact with or update them, but even that is “really, really hard,” Harris said.

He was speaking at Salesforce’s event today in San Francisco promoting its improved customer service product, Service Cloud 2. On the Service Cloud itself, Harris noted that Salesforce now allows companies to organize all their customer service conversations on the web, so the next step is to organize conversations within the company.

“All of that is just threads of information,” Harris said. “There is no more distinction.”