My event report
We did it! We got three Rust user groups to coalesce into one big meetup!
Each group had a chance to introduce themselves and talk about their projects. After that we broke off into our own groups, we kept the hangout going so it was nice to see the other groups rusticating.
In London, we split off into two groups: Hacking and Studying. The hackers worked on their Rust projects, I hung out with this group. The students I think used exercism.
I was meant to work on my first RLS issue, but ended up working on an on-boarding guide (still very much an WIP) for developers.
The items of note were a new window manager written in Rust called lanta and helping someone improve their Rust experience in emacs by pointing them to emacs-racer.
I think for the next mega meetup, I'd like to have people volunteer to share their screen at regular intervals so people could watch the magic that is writing Rust code! 
Lots of thanks and praise should be given to @pflanze, @therealjpster, Claudio and Enrico for their effort to organise their groups and then get the google hangout working. I really hope this happens again!