Office 15: What's Microsoft's new mystery application?

There are reports that a new early build of Microsoft's Office 15 have escaped the Redmond halls. More interesting than the mere existence of these pre-alpha build, however, is another mention of a new application that will become part of Microsoft's next-generation Office suite.

Despite the fact Microsoft only began shipping Office 14 (a k a, Office 2010) a couple of months ago, an August 20 Softpedia report (via the Russian website Wzor) claims there's a new Office 15 build floating around.

Softpedia's report also includes something near and dear to this Microsoft watcher's heart: a new codename. "Microsoft Limestone Integration Application" (also known as "Microsoft Lime") is a new application development element that will be part of Office 15, according to information that allegedly is part of the newly leaked build. (Update: One of my contacts says Lime is just a user-interface utility for Office, and probably not considered a new application in and of itself. Update 2: Microsoft blogger Rafael Rivera agrees and shares a bit more on Lime/Limestone....Nonetheless, it still sounds like there is a new Office 15 app coming. Read on....)

Stephen Chapman noted on his Microsoft Kitchen site, back in early June this year, that there were indications Microsoft was planning to add a new application to its coming Office suite. Chapman connected the dots and discovered a mention of "a major new feature" coming to Office 15 via a LinkedIn profile of a former Microsoft intern. That intern worked on the Excel team.

That's not a whole lot to go on, but it's got me thinking Limestone/Lime the new mystery Office 15 application could involve integrating Excel with another technology. Could it be some kind of business-intelligence-related app? Something to do with charting/data visualization? Hmmm.

Robert McLaws, a Microsoft consultant and former Windows blogger, offered a possible (and convincing, in my opinion) guess as to what the new mystery feature might be: "I’d say that the new app is most likely the extension of the co-authoring features of Office Web Apps into a shared desktop runtime. Think about it… why were Groove’s best features missing from the last release? Likely because they were being re-architected into an Azure-based next-gen real-time collaboration platform."  (McLaws emphasized this is just his own speculation and not based on anything from Microsoft about its Office 15 plans.)

One last point: According to Softpedia/Wzor, Office 15 is planned for delivery in early 2014. I'm skeptical of that date; I'd say 2012 or 2013 is more likely, given the Office team's typcial two- to three-year development/release schedule (and that group's tendency to under-promise/over-deliver so as to ship "early," rather than late).

Microsoft, unsurprisingly, isn't commenting on anything related to Office 15. "Wave 15 is currently under development, but we have nothing further to share at this time," a spokesperson said on August 20.

Any guesses of your own as to what kind of new app Microsoft might add to Office 15?