During the conversation with Jerry, where I waxed lyrical about cancel buttons, I also banged on about the importance of differentiating between a page's "hotspots" that are links and those that are actions. For example a link is something that simply changes pages, like taking you back to the homepage, while an action is a hotspot that saves a document or puts in edit mode. It's important to distinguish between the two on a page.
Obviously this is merely my opinion and is open to change. After talking about the redundancy of the "Cancel button" and the resulting comments you guys made I found myself changing direction. You were right - it's not about what we think the user should or shouldn't see. It's about giving them what they are used to working with. A cancel button for example, where it seems fitting.
Well, what about action buttons then? Personally I think that anything that is an action (Edit, Save, Submit etc) should be a button and anything that a link (Home, Return to View etc) should be, well, a simple link. You can see this in effect when you use Hotmail:
Notice how there's a row of pseudo-buttons above the messages. Each one is an action. Notice also that there is a set of simple links to the left of the messages that take users to different folders. It's easy to distinguished between them and they remain constant throughout the Hotmail interface. Users like this (I think) and it's how I like to design sites. Although my buttons tend to look more like buttons.
Again, I am open to discussion and the fact that some of you may disagree entirely.