Microsoft Office 2012 (the 15th version) is now up to build number 15.0.2621.1000.
According to Winreview.ru besides the build number, little else is known at this time, "development of Office 15, known as Office 2012, smoothly and quietly proceeded to step M2. First assembly after Milestone 1 was Office 15 (2012) 15.0.2621.1000".
Microsoft Office has become the staple product for productivity. While others have tried to nudge into Microsoft's territory, few have been able to make a dent in the marketplace. One of Microsoft's largest competitors is OpenOffice.org, despite being free, has yet to attract the attention of more than a handful of companies and government organizations.