Hi Eliav,
You are correct that NetMeeting is no longer shipping (but still supported in XP through the XP life cycle). In Vista, Meeting Space can be used as a replacement for app sharing, file transfer, and simple messaging, and it has similar "inside the firewall" limitations, requiring IT department involvement to enable internet scenarios (Teredo/IPv6 enabling).
Remote Assistance and Term Svcs Remote Control are similar (same protocol is used), although the user experience is different. Firewalls can be configured to allow port 3389 traffic for internet use, but IT departments are often reluctant to do this. Remote assistance is really a different scenario than collaboration, and the clients are designed as such.
SharedView works both inside the firewall and across the internet, and is also a good solution for enterprises for ad hoc collaboration, as it will get through firewalls using HTTP if necessary. SharedView actually requires internet access as all traffic goes through the SharedView service. SharedView is not a Windows Live application from a branding perspective though - it's available for download at ideas.live.com as that site is Microsoft's central beta location.
Hope this helps - let me know if you have further questions.
Thanks,
Cameron
