Telenav employee here - we've been navigating exclusively on OSM since June for both iOS and Android (Scout Maps App). We also acquired Skobbler earlier in the year, which navigates using OSM if you're outside the US.
Definitely check out our dev site, which admittedly lacks some polish but is coming along (http://developer.skobbler.com/) and let me know if you'd like to talk to one of our SDK guys - they always want to talk to devs about their specific use cases.
If you're developing on iOS we've recently created a pod - http://cocoadocs.org/docsets/ScoutMaps-iOS-SDK/2.1.0/
Good luck!