Two stories came across my FriendFeed feed back-to-back this morning:

1. Compete: Facebook US Traffic Nearing Google, Yahoo – http://www.techcrunch.com/2009/06/09/compete-facebook-us-traffic-nearing-google-yahoo/ (via http://ff.im/3Lnxo)

2. Study shows only 10% of Twitter users tweets – Cnet Asia – http://asia.cnet.com/blogs/infochat/post.htm?id=63011357&scid=rvhm_ms (via http://ff.im/3Lnxh)

So when will we have some accurate assessments of exactly how much traffic is being driven by social media? And is 80/20 (or even 90/10) a good enough ratio of sign-ups to actual active users to justify marketers investing significant time in these outlets?