I PM'd Marriott Concierge to get clarification, and received the following this morning:

"This was new to me too. I was working under the understanding that it was only Monday through Friday. I have researched this and have learned that at all JW, Marriott Renaissance, and Autograph Collections, outside the US and Canada you are entitled to a free breakfast 7 days a week. You generally get it in the concierge lounge if it is open, when it is not or if the hotel does not have one you receive it in the restaurant.

Let me know if this has not completely answered your question.

Regards,
Ira"

I said thanks for the clarification, and then suggested he pass along to website folk to match the verbiage in the 2 links that people have posted. If by chance there was an issue re: this new benefit, it could create difficulties if a guest had a printout showing the bennie & the hotel printed out the T&C w/o the new verbiage.

Cheers.