I require a demo PhoneGap application; please see below, this is already complete for Android and access to the repo can be given to the selected freelancer;
1. PhoneGap app (html+js):
a) start/stop location service
(a) requires to interact with the native code (you should replicate this for iOS).
(b) requires a background service running (in principle) for ever which should be able to wake up the PhoneGap app when notifications arrive.
2. Native background service
a) read settings from their server
b) depending on settings in (a) listen to location changes
c) when a location changes, send a request to their server to get near venues
d) if there are venues (more than one), wake up the PhoneGap app with the list of venues.
And then there is
3. Push notification
a) you should use APNS
b) push notifications are intended for "new friends", "new comments"