Stamps.com laid off approximately 150 employees, it announced yesterday. "We will continue to focus on building our core Internet Postage business, which remains the category leader with more than 300,000 active customers, and are moving to deploy our iShip service to corporate clients," said Chief Executive Officer Bruce Coleman. Stamps.com, founded in 1996, provides Internet-based mailing and shipping services, allowing customers to print postage over the Internet.