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

1. Compete: Facebook US Traffic Nearing Google, Yahoo – (via

2. Study shows only 10% of Twitter users tweets – Cnet Asia – (via

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?