What makes a design intuitive? is nice and readable short article about the two ways to make an interface that people will call intuitive.

Designingembraceable change is a follow-on that talks about how to introduce a new UI to an existing community. This has relevance to Agile projects that are continually tinkering with the UI.

The series ends with The quiet death of the major relaunch. Here's a trivial example of the approach:

At eBay, they learned the hard way that their users don't like dramatic change. One day, the folks at eBay decided they no longer liked the bright yellow background on many of their pages, so they just changed it to a white background. Instantly, they started receiving emails from customers, bemoaning the change. So many people complained, that they felt forced to change it back.

Not content with the initial defeat, the team tried a differentstrategy. Over the period of several months, they modified thebackground color one shade of yellow at a time, until, finally, allthe yellow was gone, leaving only white. Predictably, hardly a singleuser noticed this time.

The key point in this last article is this:

Our findings show that consistency in the design plays second fiddleto completing the task. When users are complaining about theconsistency of a site, we've found that it is often because they arehaving trouble completing their tasks.