The advance of smartphone market share continues unabated, with smartphones now representing 40 percent of all mobile phones in the U.S., according to Nielsen. From GigaOM:

Forty percent of mobile consumers over 18 in the U.S. now have smartphones, according to July 2011 data from Nielsen. Android continues to be the top performer with 40 percent share in the U.S., according to Nielsen, up 1 percent from the second quarter, while iOS remained steady at 28 percent. BlackBerry fell 1 percentage point to 19 percent over the same period while Windows Phone 7 and Windows Mobile combined for 8 percent, down 1 percentage point.

Read the full Nielsen report and GigaOM's report. Via textually.