It's been discovered on a Microsoft careers site that there's a position open for a marketing job with the Office 15 team which mentions an "Office App Store". Here's the job description:
As we launch Office 2010, we'e beginning the process of planning for Office 15 and are looking for a Product Manager to drive Office 15 strategy for partners.
This position is responsible for the strategy and planning including identifying key scenarios that allow partners to make money on Office platform – across LAR's, VAR's, SI, ISV's and Outsourcers. A key output includes an end-to-end business plan that informs Office Engineering and drives our business forward. Work includes defining the product value proposition, key scenarios and requires the use and understanding of tools like MOA (Market Opportunity Analysis) and a perspective of competition to prioritize future investments. You'll drive innovation agenda that excites our partners in areas like "Office App Store" This position will also be responsible for working across Microsoft with teams like Windows Phone, Windows 8 and Azure to ensure alignment with our business planning.