Being able to set a channel across various teams would be a great feature.

Not having this makes me want to update the code and just build it myself.

It looks like the feature is now experimental.
https://docs.mattermost.com/onboard/shared-channels.html

But it would appear to allow sharing channels between different instances, and not between different teams in the same instance. 😕

Perhaps this is coming soon? https://docs.mattermost.com/administration/important-upgrade-notes.html mentions prepping database for new "Shared Channels" feature.

Would also be nice to have the ability to share a channel with just select teams (rather than all teams).

Would love to see this. This is one of the things keeping us from moving to teams.

we have a small enterprise (35) people but we are not from the same areas but we share some common information, is there any possibility to share channels among teams?

Very good idea. Especially social channels are more useful if they are team-independent. While creating another team containing these channels would work, you'd always need to switch between teams to view these channels, which is not very user-friendly.

Same as https://mattermost.uservoice.com/forums/306457-general/suggestions/15369939-global-common-channel-across-teams which has 22 votes. That totals 50 votes!

yes, that would solve our problem.

As now there is a locking to a dedicated team for a user. If a user belongs to more than one team, only direct messages from other members (of other teams) will be notificated instantly.
If the user belongs to a channel of the other team, there will be no notifications of this channel, as long he has not changed the team accordingly.
Enable this feature will lead to some great power: organisations will be able to communicate to all teams over shared channels (eg containing all collaborators) and teams having their own plattform with all the specific channels they need and not bothering all the other when chatting....