Office 14, the successor of Office 2007 will be named Office 2010. Office 2010 is in limited beta at the moment a more broader beta is expected in the next few months. The final release is expected in Q1 2010.
For Exchange 14 the same name will be used as Office: Exchange 2010. There has been a little public info about what will be new in Exchange 2010, only some videos on the next Outlook Web Access. It is expected that more information will be available in the next weeks.
Update: screenshot of splashscreen Word 14: