Auto-thumbnail from post
 

Hi
I'm planning to switch theme, especially after I came over this incredible customizable theme.
I wonder if its possible to get thumbnails displayed in the blog's post list.
More precisely, in my posts, I place a top image just below a more tag. On the blog's front page (the post list) I would like a thumb version of that top image to appear - like here on Dolcevita.no.
Is there some kind of thumbnail support like this included in the theme - or some way to make it happen?
I might be asking for a lot, but the thumb should appear without me having to upload the top image after the theme is activated. This might sound odd, but I've tried several plugins where this regrettably is necessary - meaning I would have to go through all 250 posts to make the thumbs appear appropriately. (With the post-thumb plugin I've used till now - which is no longer maintained - the thumb is generated the first time the page is viewed.)
Thanks - also for providing such a brilliant theme.
Kjetil