Get The Image is great plugin for related functionality. You will need to configure funciton call a bit, but it will be able both to scan for image and save it into thumbnail for you. Was writing quickly and messed up a bit. What it can do is save found image into custom field (which might or might not be what you want). If you want to actually make featured image out of it – that is going to be considerably more complex.
I use the Auto Post Thumbnail plugin for doing just that on this site and it works fine. First image in a post becomes the featured image every time.
You may find the answer in this tutorial : How to Set a Default Fallback Image for WordPress Post Thumbnails
Add this in
functions.php
in your theme folder :And this in your template, where you want to show the post image :
EDIT : much better, thanks Chip Bennett
Get The Image is great plugin for related functionality. You will need to configure funciton call a bit, but it will be able both to scan for image and
save it into thumbnail for you. Was writing quickly and messed up a bit. What it can do is save found image into custom field (which might or might not be what you want). If you want to actually make featured image out of it – that is going to be considerably more complex.