Slack 推出的新功能 Shared Channels：「Introducing Shared Channels: Where you can work with anyone in Slack」。
Shared Channels are a new kind of channel that connects two separate organizations, creating a common space for both sides to make use of Slack’s communication features and platform integrations when working together.
在截圖可以看到界面上，左半部會以 Shared Channels 顯示：
這邊也有提到 Shared Channels 需要透過管理員核准：
Accept the request: The other organization’s admin will receive a direct message from Slackbot, from which they can accept your request and add the channel to their workspace.
這樣就不用另外再開 guest 了...