How does that work? Is it tied to a Google account? And in that case the account could just be transferred with it...?

Unfortunately for the 8,000 people chosen for Google's Glass Explorer Program, Google can (and probably will) deactivate your device if you try to sell it or give it away. If you suddenly become strapped for cash or decide you don't like Glass, tough luck.

Unless otherwise authorized by Google, you may only purchase one Device, and you may not resell, rent, lease, transfer, or give your Device to any other person. If you resell, rent, lease, transfer, or give your device to any other person without Google’s authorization, Google reserves the right to deactivate the Device, and neither you nor the unauthorized person using the Device will be entitled to any refund, product support, or product warranty.