Foursquare is for Customers not Staff
If your businesses is starting to use Foursquare, offering incentives and rewards for checkins and mayoralties, may I offer one small word of advice...
If your staff check in to work with foursquare it defeats the whole purpose for your business. Your staff will always be the mayor negating any incentive for customers to keep trying.
Ideally you'd like to have a new mayor every few days, some healthy competition amongst your frequent flyers not your staff that have to be there everyday anyway.