Excel Exploited, Microsoft released security advisory
Symantec reported that they are receiving submissions from their customers that contain suspicious Microsoft Office Excel 2007 spreadsheets and the analysis shows the files is exploiting a vulnerability in Excel. Microsoft has released Security Advisory 968272 for this incident:
Vulnerability in Microsoft Office Excel Could Allow Remote Code Execution: http://www.microsoft.com/technet/security/advisory/968272.mspx
Do not open attachments in email especially if you are not expecting one, make sure your antivirus is capable of scanning email contents, and please use Mailwasher or ePrompter to delete bad emails!