goodroi - 6:23 pm on Aug 12, 2013 (gmt 0)
Personally I tend to stay away from mobile apps when trying to generate traffic signals. Mobile apps can drive direct traffic but in my experience they can also divert mobile web traffic away from the main site and towards the mobile app. Of course you could argue that mobile apps can boost branding which will then later boost type in traffic and branded search terms.
From my testing I do see a positive impact on Google rankings when I boost external traffic flows (not sure if this is direct or indirect correlation).
Been there, done that, not going to repeat anytime soon.
Everyone's situation is different but as for the sites I am currently dealing with I would not use a mobile app to boost Google rankings. I do use mobile apps for other reasons.