Could be the Office Web Apps that MS have announced Orxetaian. A far as I can tell it's a cut down version of Word, Excel and P.Point and you have to sign up for something called SkyDrive. Not a new idea but MS will market & invent it as if they thought of it. A good way forward as it's totally internet based and you can setup your shared folders with other Windows Live users.
I couldn't get it to work but I think it's not yet available outside of the US & UK.