The Wall portlet allows users to post messages on another user's page, similar to Facebook's wall. You must be friends with a user to post on their wall. Wall posts are visible to all users who are a friend of the respected user. The Wall portlet can only be added to a user's personal page.
The Wall portlet is a part of the Social Networking portlet package in 6.x; in versions prior to 6.x it is a part of the World of Liferay portlet package.
Feature: Wall-to-Wall #
The Wall-to-Wall feature allows you to view only the messages that have been posted by you and the user your are posting to. The Wall-to-Wall feature is NOT a private wall post between you and the user. To view a Wall-to-Wall with a user, go to your Wall portlet and click on the 'Wall-to-Wall' link next to one of posts the user has posted to you.