"Google+ To Take On Foursquare With Upcoming "Check-in Offers" Feature. It looks like Google+ is adding a feature that will allow users to "check-in" via the Google+ mobile application in order to receive a time-sensitive deal or discount." - from TC
It looks like an idea about "do it yourself" check-ins is more than alive. Great! It is exactly what we offered in QRpon and Places for Facebook. You can really can create "own Foursquare" with exiting databases for places. With Facebook Places in our case.
The next logical step is to create check-in for things (not only for places). It is what our QRpon project offers.