In 2008, Microsoft launched worldwide legal action against numerous defendants over their selling of high-quality counterfeit Microsoft software via online auction websites. One of the most interesting tidbits to arise out of this action was the existence of the so-called Blue Editions of popular Microsoft software, including Office 2007 and Windows XP. (And presumably Vista, although it appears that no one was selling counterfeit versions. You know people really hated Vista, when the pirates wouldn't even bother to rip it off.)
While the company never directly acknowledged the existence of the blue editions of Office 2007 or Windows XP, numerous technical sources stepped forward to clear up the confusion.
The Office 2007 Enterprise Blue Edition, as it is known in both technical manufacturing circles and hacker circles, is actually not a real Microsoft product at all. There is no Office 2007 Blue Edition, whether Enterprise or not. However, what does exist is a copy of Microsoft Office 2007 Enterprise that is provided to certain Microsoft technicians and to computer manufacturers known as OEMs (Original Equipment Manufacturers). That DVD that the software comes on is colored blue.
As is often the case in technology circles, whatever the official name of this special version of Office was, those around it developed their own slang terminology instead. Hence, the DVD with Microsoft Office 2007 Enterprise for OEMs and Microsoft technicians became known as the Microsoft Office Blue Edition.