Marc and I worked together for many years in Office. But I think he's stretching the analogy to say that adding Groove to Office has the same significance as when we added Outlook.

For one, email was an established tool across businesses and individuals, and certainly within corporations when we shipped Outlook in 1997. If anything, Outlook was a late comer to the communication suite. I don't know anyone who uses Groove today (other that MSFTees). It's positioned as a peer-to-peer collaboration tool. But I don't think the benefits of peer-to-peer as opposed to web-service are well established.

Second, MS is adding Groove to a niche "Enterprise Version". When we added Outlook to Office in '97, it went into the Standard version. I later heard user surveys indicating that as many as 30% of upgrade sales were due to the inclusion of Outlook in Office. Groove is NOT going to be driving significant sales of Office.

Quoted: If you think back to when Outlook was first included in Office, it came at a time when email wasn’t a standard part of the IW desktop, and most collaboration was document based. Now email is ubiquitous, and Outlook is at the center of many individual information worker’s day. With Groove we hope to transform the ways that teams work together, using the workspace as the framework for efficient collaboration, and providing another place and tools for work to happen.