Draft posts... what should they display for 'date posted'?

I've been using unpublished posts as a way to create planned blog posts for later... then, when I have a chance I go back and finish them up and mark them as 'Published'... but I just noticed that when I do that, the published date is the date on which I originally created the unpublished post. I can certainly understand why that is, but I'm curious as what everyone else expects?

I'd like the 'posted on' date to reflect the date it was first made accessible/visible to the public, so whenever it first posted if it is posted as visible, or whenever it is first made visible.... as it is now, I could create a draft post, then create 3 or 4 more posts (which I post as visible) and then, when I go back and mark the draft as ready to publish, it appears 3 or 4 posts down in my RSS feed (and on the site)...

So what do you think? Should posted on reflect the date the post was created, even if it was never published, or the date/time at which it first became visible to readers of the blog?