I had forgotten how I signed up for eMarketer which actually dumps some useful analysis in your inbox. I didn't find the original eMarketer info but I did find this roundup of valuable external data sources (which does include eMarketer)
https://docs.google.com/document/d/1e0E3Vy6LIDP1Q15mhYh-Pp_2Uli-kVwg1xqv3j3dNWQ/edit?_escaped_fragme...
#googplus