Comment on How to Share virtual terminal SSH between mutliple logged in users with screen / Create multi user sessions with GNU screen by sergey.
For Windows:
I have written Windows Desktop Workspace manager with automated terminal for CYGWIN.
Each terminal window has built-in TELNET or TELNET-TLS server that allows to share terminal session with remote users via TELNET protocol. Check it out.
http://sergeybelous.com/terminal-session-sharing/
Shared session is persistent and can be accessed from anywhere by TELNET or TELNET-TLS client.