Jeff Attwood explains, as only he can, Fitts Law.
What I like about this post is that he uses Google's Gmail and Wordpress.com's post editor as examples. The former as bad and the latter as good. Both of these I use regularly.
While what Jeff says about these interfaces is correct according to Fitts Law, I would ask him - why so clumsy with the mouse? Click what you mean to click... I kid of course.
In defense of gmail, the buttons are all large and clearly marked. Though I can see where having Archive as a button and Report spam as a smaller less easy to click text link would make miss clicks harder. Wordpress.com's counter example of the Publish button vs. Move to trash illustrates this point beautifully.
Having said all that, I'm sure I'll miss click for weeks on end now.