Mark,
Low-acidity wasn't a defining part of the vintage to my mind. There were some wines I thought quite fat- mostly Right Bankers such as L'Angelus, Clos Fourtet, La Gomerie, La Tour Carnet. And a couple of Medocs like Pichon Baron. Most of those St. Emilions are definitely in a modern style, I attributed the low acidity to "Parkerization" as much as vintage.
But a variety of other Medocs- Leoville Poyferre, du Tertre, Montrose spring to mind- had acidity that fit my parameters for "normal" in Bordeaux.
To me, 1999 was a vintage characterized by light to moderate tannins, medium concentration of fruit, more aromatically advanced than most. All of those things mean that in most cases I'm drinking on early end. Low-acidity would make early drinking even more suggested. As I said before, the Montrose is only one I intend holding past it's 10th birthday (well, maybe a bottle of the Poyferre in the interest of science). PLans can change as I retaste in future, of course.
take care, Dale