T-Mobile has already announced that the Samsung Galaxy S4 will be available for its customers on May 1st. The phone will be $99.99 down with monthly installment payments due for the rest of the phone's cost. Over the weekend, a leaked Staples document had a tentative May 30th launch date for the Samsung Galaxy S4 on Verizon. While this would be more than a month after AT&T's release of the phone, Verizon usually is the last to market with multiple carrier releases as the nation's largest carrier is known to rigorously test its handsets.
source: AT&T via Engadget