What’s going on in Brentwood?  Recently a widely popular Peet’s Coffee closed up shop, allegedly due to a jack-up in the rent, sending out shock waves among locals.  And now, right next door at 11754 San Vicente Blvd , a perennially busy Gaucho Grill has pulled out as well.  The melancholic letter on the door lets us know that the date of closure was March 12th.  Even while taking these photos, stunned Brentwood residents who had come for dinner were expressing their disbelief and protestations to me.  With cultish Pizzana, and upcoming Mendocino Farms and Jon & Vinny’s Italian, the Brentwood dining scene appears to be rapidly changing…