Leo Laporte is annoyed by some Buzz glitz, and has gone back to good old blogging. The made me think of the difference between social networks and content creation. In a nutshell, social network and content management can be viewed as separate tools. Most of the tweets, buzzes or LinkedIn updates of any long term value I see are actually links to posts. This means that social networks are transport tools for the actual goods, not unlike public transport. You can use it to move around, but you do not want to limit yourself to one type of transport or one carrier.
John C. Dvorak, noted that cloud based service (of which all social network services are) are fickle. Other note that it is simply misused. The case put forward by Efrat is that recruiters don't leverage social network with other HR tools, but simply use it to flush out information, and do not continue the discourse, either on or off the social network of choice.