Anderton
They are planning on approximately quarterly point releases, and incrementing the version number every year or two (which would at that point trigger an update cost).
Craig,
There was one very important nugget I noticed in your original post (among all the other useful nuggets). The choice of a
"quarterly release cycle" appeals to me as a user. The excitement of the monthly update is starting to lose its shine. Of course I can always wait a couple of months to update but, as I understand it, this will not save any time since all of the previous month's updates will be installed to allow roll-back if needed. (Please feel free to correct me if I have misunderstood how updates work but try to be gentle, we artists are a sensitive breed

)
Of course, a monthly update would appeal to some and it probably helps with the marketing.
Thanks for keeping us updated on Window 10, I reside on a desert island in the south seas (Australia) and am therefore well away from all the IT action.
Cheers,
R