Apple is continuing its roughly biweekly release cycle for developer builds of OS X 10.7.4, pushing out Build 11E52 for testing yesterday.
As with the last several builds, Apple lists no known issues. The company is also asking developers to focus their testing on Graphics, iCal, Mail, Printing, and Time Machine.
Work on OS X 10.7.4 continues as Apple is also pushing forward on OS X 10.8 Mountain Lion, which is due for release in "late summer". Earlier this week, Apple released its third developer preview of Mountain Lion for testing.