Jon Udell at InfoWorld - The importance of interaction data:

"Rather than consulting a dictionary to propose alternatives to misspelled words, Google instead mines its own database for patterns of use. If statistics show that a query for "Boswerth" is likely to be followed by a query for "Bosworth," the search engine will make that connection for you.

Discussions of software as a service tend to focus on its obvious benefits: zero-footprint deployment and seamless incremental upgrades. Less noticed, but equally valuable, is the constant flow of interaction data. The back-and-forth chatter between an application and its host environment can be a drag when connectivity is marginal and it precludes offline use. But when this communication flows freely, it paints a moving picture that shows how individuals and groups are using the software. As they watch that movie, developers become intimate observers of their users. They can't help but think of ways to optimize the patterns they discover, and, as a result, the software improves gradually and continuously."