This Dave Winer post on firefox ( http://www.scripting.com/2005/11/19.html#convincingFirefoxToSelectallOnClick ) reminded me to post my thoughts on UX consistency.
By default when we design a User Experience we default to being consistent with some standard (a convention or pattern of UI, a corporate guideline, a previous version, etc.). It's a completely valid approach.
I've seen some people turn this from a default position to an inflexible rule. That is, they will, knowingly or not, sacrifice for consistency even those deviations that, by their own admission, are better for the user.
To What End, Consistency?
The reason we make UI consistent is to Make life better for our users and NOT to be consistent (a tautology).
A Tool, Not a Dogma
Consistency is just one of many tools we have available to create that better experience.
Although I, in general, start from a position of consistency, all things being equal, I'll take an UI inconsistency that makes a better user experience over a consistent UI that makes it worse.
Users can absorb some inconsistency
In some cases, inconsistencies are completely unnoticed by our users.