I mentioned UGC the other day and then I got invite from Google Map again to become one of their local guides. I think as long as you post or review something on Google Map, it will try to convert you to become a local guide by sending invite to your gmail account.
I used to checking-in / posting pictures on Facebook and Foursquare but eventually I got churned. Google Map is quite suitable for on-demand / real time site discovery and location-based search (particular convenient for travelers who have limited local information and that’s why they need guides). The review / rating / uploading information features have been on Google Map for a while but I didn’t notice local guides until recently. Google finds the potential to collect large data by encouraging its uses to generate content and facilitate community building (off-line meetup and online post).
To encourage user to contribute more content to Google Map, Local Guides uses some gamification with non-monetary incentive such as level to reward its content creators.
Weekly stats report also helps the program keep some user engagement.