The communication aspect of a community runs from the formal (newsletters, bulletin boards) to the informal (chatting with neighbors). Without the means to communicate, the various members of what would otherwise be a community are isolated. Communication is also the lubricant that keeps other aspects of community working. Actions by the government must be communicated to members in a reliable way. Commerce flows more freely when there is a means of advertising available goods and services.
I believe that both formal and informal means of communication must be present in order to have a healthy community.The key is to have various channels of communication and to ensure that communication multi-directional (and multi-modal with current technology).