The last version of wordpress is awsome and add a lot of needed features but there some bits where I was more happy with the old one. When you write a new post, the category list is now positioned below the Editor, just after the tags. Why so far and not where it was before, on the right hand side. There is space over there…

Ok, if they choose to place it where it is it doesn’t mean it has to be there forever. Let’s get it on the side, just after the “save” and “publish” buttons.

After a bit of analysis (opening firebug and reading basicly) I see that the file used to build the “post new” page is edit-form-advanced.php in your wp-admin forlder. Around line 216 you should get the interesting part:
<div id="categorydiv" class="postbox <?php echo postbox_classes('categorydiv', 'post'); ?>">
<h3><?php _e('Categories') ?></h3>...

So cut the div (line 216 until line 249 on mine) and paste it above

<div class="side-info">
<h5><?php _e('Related') ?></h5>

around line 160. Your sidebar should look like this now:

Good start, next we will se how to style it so it looks more….usable.