What is the recommended best practice for positioning "action" buttons on a user input form? Our application typically has one or two positive action buttons (eg. submit, next, save), and one or two negative buttons (eg. cancel, suspend). In the past I've always assumed that positive actions should be on the right, but a quick glance at Jakob Nielson's website seems to indicate that this is not the best approach.
What would you recommend?
I would say that there is no best position. You should always make sure that a user can indicate a positive button and a negativ button. So giving a negative button a red symbol or a red background color, he will notice, that he might read the value of the button before clicking it.
The position depends much on your layout. I usually also have positive buttons at bottom right, but sometimes that position is not the best.
Be conscious of where the eye flows down your application. If you have text field after text field, and the flow of the page follows a straight line, the most appropriate place for your positive buttons is probably in the the same straight line. This positioning encourages a checkout or a final transaction.