As of 8:30 am today, NCESSE had not received any word as to whether the launch of STS-134 will be postponed. However, the Daily Beast is reporting that the launch of STS-134 may be put off until April 29. Until there is official word from NASA, we have no choice but to assume the launch remains scheduled for April 19. A launch delay would obviously impact both submission of the flight ready experiment samples, and the launch viewing plans.
A summary of the situation is found on msnbc.com.