I've noticed that this grass is becoming popular in theme parks and other venues. I live in Northern California and have seen it at the new Stanford Stadium (not the turf but in the landscaping), Marine World, Great America, and I have seen it at Disneyland and Legoland - can you tell I have kids :-)
Anyone know what it might be?
I've been to LegoLand many times (I have a six year old) and have wondered what that grass was also. The grass I saw (it's all over the place) was 12 to 24 inches high and not meant to be walked on. I don't think Carex pansa can grow more than 8 inches high.
The posibilities I see are European meadow sedge (Carex remota) or Berkeley sedge (Carex tumulicola). Both grow 1 to 2 feet tall and should not be mowed for the meadow look.