Heck Estates, owned by Gary Heck of Korbel
Kenwood, Lake Sonoma, Valley of the Moon
Where he's turning brands into labels (same production facilities, same winemakers)
Trinchero, the Sutter Home family
Folie a Deux, Montevina, Napa Cellars
Not a consolidation but the latest sale I'm aware of is Limerick Lane, a small winery that's been around quite a while and known for their Zinfandels. Their equipment and property sold to a local person. The sale didn't include the liquor license so it sounds like the Limerick Lane name is gone.
Following is a list of the big guys and some of their major holdings (not a full list). With all the changes it'll probably be out-of-date by the time you read this.
Spirits maker Brown Forman
Fetzer and Sonoma Cutrer though these are reportedly for sale.
World's largest wine company, headquarted in NY, Constellation Brands
Blackstone, Clos du Bois, Franciscan, Mt Veeder, Ravenswood, Robert Mondavi, Simi
Headquartered in London Diageo at one time owned Burger King
Beaulieu, Chalone, Sterling
Gallo owns lots of labels for wines made at their Modesto plant, plus Gallo Sonoma
They bought Napa's iconic Louis Martini Winery a few years ago
Jackson Wine Estates, the Kendall-Jackson family
Arrowood, Cardinale, Freemark Abbey, Hartford, La Crema, Matanzas Creek, Murphy-Goode
Hartford and La Crema were started by Jess Jackson, the others were purchased
Treasury Wine Estates was formed when Foster's spun off their wine brands. Treasury is reportedly for sale (plus Foster's is in the middle of a hostile takeover)
Beringer, Chateau St. Jean, Meridian, St. Clement, Souverain, Stags Leap