Some thoughts on implementation of this feature:
- any implementation of this must be entirely backward-compatible with the current (single forum) Discourse structure
- Topics, Categories, Groups, Badges and Notifications must all be scoped to a specific forum. Anything else?
- Site Settings need to be (all? most?) scoped to a forum
- user must be able to get a list of forums they are participating in; this probably belongs on the Profile page
- home page behavior must be different when there are multiple forums; what to show before user chooses a forum to enter?
- searches must be (always? optionally?) scoped to a forum
- admin/moderator status must be scoped by forum
- Profile options probably need to be a combination of global and per-forum
- email digests should consolidate activity across all forums in which the user participates
Plenty of work here. Are there any other particularly scary aspects that I’m missing?