You can now override the "from address" on email alerts with the Default Workflow User. This makes your email alerts seem more personal and easier for users to reply to.

To use the default workflow user's address as your From Email Address in an email alert click Setup ➤ Create ➤ Workflow & Approvals ➤ Email Alerts, select an Email Alert, scroll down to the From Email Address, and select the Default Workflow User's email address.