From what I've read of PLATO it seems like it was a pretty powerful system, with some features that in retrospect seem way ahead of it's time, especially when compared to BBS which seemed to be far more popular. According to Wikipedia at least (super accurate, I know) the last production system was shut down around 12 years ago.
Are there any known running versions of this system which can be access via retro machines today via WiFi modem or similar?
The Previous poster has inaccurate information.
There is a PLATO installation that has been set up for retrocomputing users @ IRATA.ONLINE. If you go to the website, you'll find information about the service, how to connect, as well as a technical section that is full of information on creating terminals to use with the service. Thus far, we have a working terminal implementation for Atari 8-bit machines, with more on the way. We also provide two source code implementations in C, and a link to a disassembly of the Atari PLATO cartridge on GitHub.
Currently, retro-computers can log onto both Cyber1.org and IRATA.ONLINE via an emulated internet modem, built from devices such as:
IRATA.ONLINE also hosts multiple meets on the weekends, to demonstrate the system, and talk with potential users, authors, and systems programmers (the latter hopefully to help write terminals).
With the combination of a rich and capable delivery protocol, a built in programming environment, and the pervasive inclusion of social networking features, retro-computing users will finally have a killer app that they can connect to, because an Atari 8-bit can't log onto Facebook, a Commodore 64 can't log onto twitter, nor can an Apple II go onto Instagram.
IRATA.ONLINE is being run as a pure labor of love, with zero commercial connection to it, there is no data gathering, no access or subscription fees, just a place to connect for retro-computers of all shapes and sizes.
Well, if scroll down to the Cyber1 section of said Wiki article, there is your answer.
Are there any known running versions of this system which can be access
Cyper1 is a service runing the PLATO software under NOS on an emulated CDC.
via retro machines today
Not realy, unless you got a real PLATO terminal. Also the requirements may be a bit to high for classic machines.
The available emulation called PTERM is available Windows XP and above, Mac OSX and various Linux/Unix machines. It's in (quite) active development.
via WiFi modem or similar?
Not sure how WiFi is related to retro, but thats more of a network issue of your machine, isn't it?
