For the first time, Research in Motion's BlackBerry platform has dropped to third in market share among smartphone users, behind Google's Android and Apple's iPhone platforms, according to a report by metrics company comScore Inc. released Friday. Android-equipped smartphones accounted for 36.4 percent of U.S. smartphone users 13 and up for the three-month period ending in April. That's a 5.2 percentage point rise in market share from the three-month period ending in January. At the same time, Apple's iPhones rose to second in market share with a 1.3 percentage point rise, to 26 percent. The BlackBerry platform lost nearly as much market share as Android gained: down 4.7 percentage points to 25.7 percent. Android first eclipsed BlackBerry -- the previous market leader -- in January's...