Only to be available from Microsoft, either at their own stores or at their online store.
This limited distribution strategy may be one way they're placating OEMs. Rather than try to ship high volume of units, it may be more along the vein of the Nexus phones. Nice reference designs but not a high volume product.
If that's the case, why bother? That is what doomed the Zune, that they wouldn't commit to making and selling a ton of units, so they couldn't compete with the iPod on price/cost. They didn't sell the Zune outside the US either.
So far, most of the buzz seems to be about those colorful keyboards/covers, which are probably optional accessories.
But there seems to be an interest in this hybrid device, since it can be both a laptop (with a good keyboard) or a thicker, heavier tablet. Of course, there wasn't a big market for the Tablet PCs that MS has been pushing for a decade now. But these should be more sleek and cheaper.