Two ways to communicate with your colleagues, business partners, and family are e-mail messages and your mobile phone. Both have their advantages, but managing your contacts, correspondence, and appointments by using two different media can be cumbersome.
Outlook Mobile Service is a new feature in Microsoft Office Outlook 2007 that you use to create and send text messages as well as multimedia messages to a mobile device from within Outlook in a manner similar to e-mail messages.
Outlook Mobile Service makes it easier to use both these media and is fully integrated with Outlook. With Outlook Mobile Service, composing and sending a text or multimedia message is now as quick and easy as creating and sending an e-mail message. After the message is sent, you can see it in the Sent Items folder in your Inbox.
For more details, read this wonderful article. It describes about the advantages, how it works and its features.