There's a small but loud group of activists in Atlanta who are sure aerial gondolas are the answer to the city's transportation woes. Looks like Vancouver (Burnaby) is actually going to do it for connecting Simon Fraser University to the city below.
The system in London works, but was not built in a very useful place. While it's a handy way to get from the O2 arena to the Excel convention centre (something people needed during the 2012 Olympics), it's very rare for a longer journey to be made quicker by connecting to it - most of the time you can go to a different station and change. While it is part of the London Oyster fares system, it costs extra to ride.
Medellin in Colombia, for example: