WiFi on JR trains?

I've seen some reports online, but nothing really concrete, that some JR trains may have WiFi onboard.

Which, if any, JR trains have WiFi (free, right?) on board? (Obviously WiFi is much more practical for a tourist to use one's laptop to get online and work while in train, vs. using 3G on an iPhone that is ridiculously expensive and much more difficult to work on. Plus I am not even sure if moving at that speed 3G would work very reliably?)

I am currently aware of only two trains in Japan that have (paid) WiFi. One are the newest train sets (N700) along the Tokaido Shinkansen (Tokyo to Shin-Osaka). And the other are the new train sets on the Narita Express (to Narita Airport).

But I believe that within the next few years, the number of trains will rapidly increase.

Furthermore, Wifi is available at many major railway stations, especially in the Tokyo area.

Note also that you will have to subscribe to a Japanese access provider in order to use most of these Wifi networks.

The Narita Express service no longer requires one to sign up for a contract or subscribe in advance. One logins in and pays the fee for a one day pass. Though I really don't think it's worth the cost for a 1 hour or so ride. Maybe if were were really on business or had a longer trip.

Subscribe wasn't the right word. On the N700 shinkansen, too, you don't have to subscribe. It is also possible to buy just a 1-day pass. However, you will do that before riding the train, as you need internet access to purchase the 1-day pass (in case of the shinkansen).

Today, on the regular Sobu Line train (which does use the same track as part of the Narita Express), there was a locked wifi service listed as Warpstar-292a69. It was in every coach of the train with full bars of reception.

http://www.hotspot.ne.jp/en/