Thing 4 - Maps and checking in

I've been a regular user of Google Maps for some time, mainly for when finding out where a new location is, and about how long it will take me to get there. The bloke did install a turn by turn voice navigation system for me, but I tend to just click on the address that I will have popped in my Google Calendar and normally can't be bothered copying & pasting into the nav system. (It is a freebie so not always fantastic on the exact details but I should use it more often!)
I've also used Facebook checkins and Foursquare - but privacy concerns means that I tend to use them very selectively. For example, I never check in at the kid's school, and I have the photo location tracking turned off for the same reason. I also have the bloke reminding me that he doesn't want me telling people that I'm not at home, for obvious reasons.
My Foursquare checkin's are fairly safe - I've only connected with one person, and I use it sometimes for the special offers. A cafe near MPOW has had a 'check in five times and get a half price hot drink' deal that I have used very happily in the past. But this week I was told that they were no longer honouring it - even though it is still showing on Foursquare itself. Which got me wondering, if the person who sets up these deals from a business moves on, what is requirement that the deal is honoured? And is the first flush of some of these location specific deals wearing off - was the uptake not great enough (the staff always looked quite bemused when I handed over my phone to take advantage of my offer) or too great for some businesses.
I helped a friend set up a Facebook page for his small business, and we discussed using offers for checkins. But very few of his customers have ever checked in at his location, and it wasn't something he tried. In his case, his core client base is not that tech savvy but for others (such as Academic libraries) it would be quite different.  I'm interested in seeing how different libraries use these options to connect with their communities...