First of all, what I want to achieve is this: I have my main page, with a div 'cont' and a php file that dynamically holds posts, stored in a database, let's say post.php.
I would like the user, by clicking a button, to scroll smoothly to the post.php page (actually load smoothly the contents of post.php inside the 'cont' div).
if you are adding the new posts dynamically to the same page you can insert each post for instance into <div id="insert the post id here, pick it from DB by your php-script, it is going to be unique for sure"></div> and then you can do with this div everything depending on your conscience
use [code]YOUR CODE GOES HERE[/code] or burn in Hell
joi has a TransitionPanel widget, which is designed for transitioning between dynamically generated content. It's very easy. Look at the example on that page, it probably does exactly what you want (scrolls between dynamically generated PHP content).