I think the most substantive takeaway from the recent Mary Meeker presentation on Internet Trends is that mobile monetization is a huge opportunity (in share of consumer media consumption) and is incredibly nascent. One perspective is that such a gap means mobile advertising will be huge.
That being said, I still have yet to see a decent mobile advertisement that didn't jar me as a user.
What are the substantive challenges that you see in the mobile space from a user experience perspective or from an industry perspective?