Apple sold 300,000 iPads on launch day. By the first week, Apple had sold more than 450,000 of the devices. We are now learning today that the iPad continues to be a big seller in the U.S. with Apple having delivered 500,000 iPads to date.

However, that strong initial showing for the iPad here in the States means that the international launch is being pushed back. "Faced with this surprisingly strong U.S. demand, we have made the difficult decision to postpone the international launch of iPad by one month, until the end of May," said Apple in a press release. "We will announce international pricing and begin taking online pre-orders on Monday, May 10."

The Cupertino-based company went on to brag about the sales success of the iPad in typical Apple fashion. "We know that many international customers waiting to buy an iPad will be disappointed by this news, but we hope they will be pleased to learn the reason—the iPad is a runaway success in the U.S. thus far."

While Apple definitely has a leg up on the competition at the moment, there are new devices waiting in the wings. HP will soon launch its Slate which is a tablet based on Windows 7 and Google is currently developing an Android-based tablet.