This is interesting; Brazil is currently carrying out a national census. How? With 150,000 LG 750GM smartphones, and a canny bit of software. Photos are here. Things that struck me - the Americans decided to build a dedicated device and it cost like hell. The operating system on the 750GM, however, is MS Windows Mobile 6.5 - these days, Windows is the cheap and nasty option! But why not, if they're going cheap?
And one of the biggest problems for the enumerators is getting access to gated communities.