Marc my words: No Web service is perfect.
The site, Trust.salesforce.com, also shows historical system performance. So anyone can see that Salesforce's NA1 component has been offline twice in February: for 81 minutes on Feb. 9 and 62 minutes on Feb. 16. Salesforce had a six-hour downtime just before Christmas. A Salesforce spokeswoman described the service availability display as "inspired by customer feedback."
For software-as-a-service to continue growing, it must be reliable. After the January outage, Salesforce chief executive Marc Benioff was quoted in news reports as saying, "Nothing runs at 100% availability." Trust.salesforce.com presumably will show that to be true--just hopefully not too often.