On the iPhone side, you simply go into the mail account settings and create a new Exchange mail account. You then specify the user's e-mail address and password. The iPhone will then use AutoDiscover to try to guess the correct e-mail server settings. If it fails, you can specify the server and domain manually.

Once it's set up, e-mail delivery is nearly instantaneous, and you can enjoy e-mail, contact, and calendar synchronization between the iPhone and the Exchange server. You can also originate and accept meeting requests.

An alternative way to configure the iPhone is to take advantage of the :

This utility enables people to create custom configuration files for the iPhone. You can configure settings for Exchange, POP3/IMAP e-mail, VPN, and Wi-Fi. It also facilitates the configuration of password requirements and restrictions on applications and camera use.

When the configuration file is ready, it can either be e-mailed to your users (assuming they already have their iPhones configured with an e-mail account) or it can published it to a web-server where it can be downloaded using Safari.