For the first time in, well, forever, I'm wondering whether Microsoft's (Nasdaq: MSFT) Office franchise is in trouble. Google's (Nasdaq: GOOG) Apps Marketplace could be giving the search king a competitive advantage in productivity software.

The Apps Marketplace is reminiscent of the iPhone App Store; it's where Google Apps users purchase and download add-ons. Last week, 16 more became available, including Gantter for project management, and Jive Express for collaboration via social networking.

Microsoft has had Office add-ins for years. But add-ins are mostly tricks and shortcuts. Google Apps add-ons are software. Google is borrowing from Apple, encouraging developers to create gimmickry for Apps in the same way they do for the iPhone and iPad.

Consider Jive Express. Users can tag content they create in Google Apps, then create discussions around those tags. Neat? Sure, but whether or not Jive or any other current Google Apps add-on is must-have software isn't the point.

As an investor, it's the pattern that matters. What's happening in this market reminds me of the battle between Siebel and (NYSE: CRM). Siebel once dominated the market for customer relationship management software -- but no more. Research shows SAP (NYSE: SAP) as the leading CRM vendor, with Oracle's (Nasdaq: ORCL) Siebel second and third. Up from nothing a decade ago,'s collaborative platform today accounts for more than $1 billion in annual revenue.

Could Google's productivity-apps superstore produce similar gains for the search king? I like its chances, but I'm also just one Fool. Please share your opinion by voting in the poll below. You can also leave a comment to explain your thinking.