This demo uses the Dynamic Components extension by Yusuf Cihan, to create a card style listview for AppInventor 2.
also see:
Horiz and Vert Dynamic Listviews
[EDIT]
With the latest version of Yusuf's extension, it is now possible to reverse the order of the cards after creating them, so that with a chat type project, you can have the latest post at the top, instead of hidden at the bottom