Marriott Rewards introduced Elite concierge service last year (don’t know anyone who would have been chosen as a member) and has now changed the name more familiar for those that belong to the SPG program.
Marriott Rewards has renamed the (non-existent) elite Concierge service as Ambassador. Not sure what the benefits of this level are and what is required for qualification.
You can access Marriott Rewards here.
Marriott Rewards has had Platinum Premier status level for a long time that hasn’t done much to its members. It is interesting to see if they can be more successful with this Ambassador one.
I was member of SPG Ambassador program for a year after putting 100 nights in the previous one. Whether you think that the program is success or not, largely depends of the Ambassador assigned to your account. Some are better than others (and mine did nothing really).