When someone new joins a team, it is your one and only opportunity to make a good first impression. A warm welcome, is laying out the red carpet, making a new person feel special and like you actually want them to be there.
He gives an example of day 1 at a new job, receiving an email with a link to a wiki page. The wiki page greets him personally, and has a list of people to meet/things to do on his first day. Last item on the list is to find the name of the next person to join the team, and change the name at the top of the page.