In Ember, we had a community-run effort to build something like this: http://emberjs.com/community/meetups/
One of the nice things about this is that meetups get added to a single data file, and people submit pull requests to add their local group. We reach out to meetups to get them to provide the information (or do it ourselves), has a whole page dedicated to meetup assets, and even have a program for people to commission custom versions of the logo for their meetup.
This has been a lot of fun, and we now have versions of the logo customized for tons of locales, designed by the local community.
All of which is to say: there’s a lot of cool, creative stuff a community team can do to help build local communities and give them a sense of belonging to a global community of Rust users.
One thing to avoid is trying to replace the functionality of apps like meetups.com, which naturally get kept up to date as an artifact of running a meetup, with a central directory of information. Maintaining links to the canonical source of location, especially in combination with a nice map visualization, is great.