Righty watches aren't a big deal for us to use because you only use the crown to set them, and you only set them twice a year. On the Apple Watch, you're going to use it all the time.
It's not even that I couldn't use my right hand, it's that I don't want a bulky $350 gadget permanently strapped to my left hand, which I frequently use for doing things. Great recipe for (best case) being irritating, or (worst case) getting smashed into stuff.
Maybe it can be rotated 180° to go on a right arm? It'd mean the button and crown positions are backward, but it'd be better than nothing. I see no mention of that option anywhere, so for now I assume you can't.
Either way, doesn't support the 4S, costs more than I'm willing to spend, and will hopefully get thinner in future releases. I'll jump on the smartwatch train eventually, but not with this one.