divorce no ring

Maria Shriver is NOT going to be the woman scorned -- she's back at it, shopping up a storm in Malibu and facing the cameras with a smile. Oh ... and without a wedding ring!

The estranged wife of Arnold Schwarzenegger sipped Starbucks while shopping with her son Christopher, 13, today in the 'Bu where the family has a home. In fact, Arnold was spotted on his motorcycle near the beach house on Saturday after spending time with son Patrick. The 17-year-old Tweeted: "Nothing could be better than going to hit up the Malibu house."

Meanwhile, Maria, 55, was contemplating some advice from her daughter in Twitter: "My daughter once gave me a great Plato quote that said, 'Be kind, for everyone you meet is fighting a hard battle.' I love that. So true."

And as a tribute to those who gave their lives for our country, she wrote: "This weekend, I'm thinking of all who gave their life, and all the families who lost a loved one, in service to this great country. You have our deepest gratitude and respect. God bless."

On a more personal note, she added: "We don't know what is going on inside of most people. On this Memorial Day, when so many are grieving in obscurity or silence, let's keep that in mind."

These are some prolific Twitter-ers! Patrick even let us know he left for New York today, writing: "Off to the airport ... and I'm going to the big apple NYC. Excited to go, but I need to keep up with the studies while on this trip." Such a good boy ...