But what is still missing is a Metro version of Office. Historically, Office has always been the showcase on how to build proper Windows applications, it's where UI innovations are first introduced: i.e. embedding, multiple document interface, icon bar, ribbon.

Since the introduction of the Metro ('modern') UI, Microsoft has not been able to really show the power and possibilities of it. Office for Metro should fix this, and show people how Metro is superior to the iOS and Android UI. Supposedly Office Metro has been in development for years (project Gemini), but as it turns out: it's not ready. And Office for iPad is.

I hope we'll hear more about office for Metro soon, maybe next week at Build?

I read that the Office branch of Microsoft allows exactly zero libraries and lines of code that they do not control. They use their own C-compiler, everything. That also means that they first need to copy Metro before they are prepared to use it. I can imagine that is quite a big task.

He stressed "tablet optimized version"

The office on my surface is just the desktop one without any optimization for touch screens. Edit: and yes, I do not think that the "touch optimized features" they are describing on that site is enough for a real rt app.

The Office for iPad looks much more optimized for touch screen devices, rather than having minor adjustments made to Office for desktop that RT looks to be using.

I'm guessing the usability differences are night and day between the two devices.

Yes, and the RT version is a pile of poop and neither version performs particularly well in a touch-only environment