PDF Preview for Outlook 2007 via Adobe Acrobat Reader 8.1 Update
May be it's too late for me but I just updated my Adobe Acrobat Reader to 8.1 and found the update comes with PDF preview handler for Office 2007 (& Windows Vista). It nicely gives me the preview of PDF attachments in my Outlook 2007. If you have been waiting for PDF preview in Outlook 2007, go and grab Acrobat Reader 8.1 at http://www.adobe.com/support/downloads/detail.jsp?ftpID=3661