Actually it was Facebook which had been hacked by the Tunisian government, apparently with help from the Tunisian ISPs. They where sharing their Foursquare locations in Facebook.
Tunisian Government Allegedly Hacking Facebook, Gmail Accounts of Dissidents and Journalists | Fast Company
'A strange bit of JavaScript has found its way onto Tunisian Internet users' internet login screens.'
...indeed.
It seems rather stupid to me that protest leaders, dissidents, insurgents and guerillas would even do such a thing as broadcasting their exact locations to everyone, using things like Foursquare and Google Latitude along with Facebook and Twitter.
Of course governments can get accurate location information from mobile phones anyway via the carriers. Foursquare and Google Latitude just makes it much easier for them.
Employers can also see Foursquare location information on Twitter and Facebook as well....'This employee is the mayor of many bars and clubs. Frequently likes to get drunk. Perhaps we should fire him/her?'