Behold: Queens

Google Transit is prepping for one of its most ambitious projects to date: mapping the New York City transit system.

Appropriately covered by Bloomberg, Google is working with New York's Metropolitan Transportation Authority and New Jersey Transit, which collectively move 9 million commuters every day.

The project has given rise to speculation about the mash-up possibilities for more targeted and localized advertising.

US companies already spend $922 million on ads placed alongside local searches and maps. Such spending is expected to balloon to $2.61 billion by 2011. One analyst estimates that local ads make up roughly a twelfth of Google's $6 billion revenue.

Read/WriteWeb points out that mashups like Hopstop already exist, but giving people instruction on navigating New York's train lines will be no easy task.

The MTA includes 468 subway stations, just 35 stations fewer than the total number of all other subway stations in the US.