I just read that they plan to put WiFi on the trains in Brisbane.
I had one of my crazy business ideas to try and do this years ago. I think it'd be great for public transport adoption. Imagine being able to be on top of your email by the time you arrive at your desk?
Of course, with mobile broadband becoming more and more ubiquitous, you don't really need WiFi on the train, so it may be too late...