Google blog:

Starting today, you can create lists of places, share your lists with others, and follow the lists your friends and family share with you—without ever leaving the Google Maps app (Android, iOS).

And:

Open the Google Maps app and find that BBQ spot you’ve been wanting to try. Tapping on the place name and then the “Save” icon adds the place to one of several pre-set lists like “Want to Go” or “Favorites.” You can also add the restaurant to a new list that you name yourself, like “Finger Lickin’ BBQ.” To recall the lists you’ve created, go to Your Places (in the side menu) and then open the saved tab. Icons for the places you’ve saved to lists will appear on the map itself.

I love the concept. Only issue I have is that I tend to move between different Google accounts and if I am logged in to the wrong account, I won’t see my place lists. One workflow is to always share place lists with all accounts, then each added place will automatically appear in all accounts.