Luke Wroblewski talks about this in designing forms too. (Presentation PDF) It all depends on what you are designing for. You might want someone to be more careful and slow down in areas and fly through others.

I find that usability is most important when there is more task / form based things going on. You also have to look at who is coming to your site… Is it someone who is dedicated enough to get through some minor usability issues? OR Is it someone new to your site and needs to get what they want quickly. It’s not always easy to balance. I do agree though that traditional rules of typography in the print world are very helpful in accomplishing this.

Good post! Thanks for reminding me about this.