The search giant announced the feature at Google I/O in May. It allows users to create lists of places, say restaurants, in Google Maps and then share that list among their friends, who could vote on which place to go to. Group members could also veto certain places on the list, or add their own suggestions.
What Google is doing is making it easier for friends to decide where to go without needing to send a hundred text messages to everyone. The group planning feature also has the added benefit for Google of keeping users inside their app instead of going to non-Google messaging apps to discuss their plans.
The group planning feature will start rolling out on Android and iOS this week. To get it, just update to the latest version of the Google Maps app when prompted.