Last week @ Cloudforce Seattle, Salesforce.com demonstrated some impressive Twitter integration into their Service application. From a CRM perspective, you want to know what your customers are saying whether in sales or service. For Sales, it helps get you to personal faster. For service, it helps you show the love. In researching similar and related technologies, TwInbox for Outlook looks promising.
Check this Microsoft Showcase video about TwInbox: Office Casual: How to Twitter in Outlook (with TwInbox).