Teare is right that Google’s falling CPC due to mobile is a big issue. Even if one day it is going to be amazing, today it is bringing down average revenue.
And as for that Facebook acquisition of Instagram, it may not impact the real threat that mobile represents to Facebook – the threat of falling monetization due to the impracticality of delivering ads derived from the web era to a mobile audience.
Mobile is this huge new inventory of ad units. That on its own is going to make ads cheaper.
The question is how long before folks figure out how to monetize it –> the theory of a Starbucks coupon as you walk by is still just nonsense.