[analog]

So they've organised a conference using Meetup? It doesn't seem to me like that's what Meetup is intended for

"Meetup's mission is to revitalize local community and help people around the world self-organize." [1]

If meetup.com don't want to be used for promoting conferences then they've got every right to shut this down.

[1] http://www.meetup.com/about/

[donretag]

What is the difference between the conference that got shut down and this conference: http://nescala.org/?

The difference is that the latter is organized by Meetup employees. A different set of rules if you work there I guess.