http://diegobasch.com/42-of-us-internet-users-have-a-faceboo...
TV advertisers are restricted to one way flow of information, so advertising is about building brand. It's difficult to convert this into conversions. On-line advertising however have accurate statistics because of the available analytical software. Advertisers stick to conversions only as it's still a wild west when it comes to accurate impressions (even Facebook has been caught cheating on viewer counts). Until advertisers cater to surfers the full potential of on-line advertising won't be realised.
I assume it's what caused the shortfall in Google IO's graph, I personally feel on-line marketing understated as a medium.
I would say that knowing the absolute reach of as many channels as possible is important including billboards etc. If you expect a 0.5% conversion rate, as long as you filter out ones that reach less than a million people a week, all of your options represent a serious return.
I ran a pricing survey there a while ago and a lot of people were willing to pay 11111111111 or 12345 dollars per month.
Seriously, did you have something to add to the conversation, or are you just pointing out random things everyone knows?
Back in 2008, I created some accounts for fun to see how Facebook worked, began sending out random requests first day to 4-5 people, next day to 4,5 people. On the third day I had more than 40 friends and was in a circle in some other country and people began writing on my wall asking how I am. Lame.