They’ll be a Leather-wearing class so they’ll share armor with Bear Druids, and while they can use fist weapons and one-handed axes/maces/swords, it doesn’t look like they can use shields. As a Tank you’ll probably be using Polearms or Staves. You won’t be able to Block, so you’ll be relying on Dodge and Parry like Death Knights.
I got to play a little bit of the starting experience during Blizzcon, although not enough to get more than a couple levels, so this is just an initial impression that’s likely to change. Early on the reliance on regenerating Chi to do your basic Jab attack seems a bit of a hindrance. While you can use Light/Dark Force abilities in the meantime, Chi still felt too slow when you need it.
It might be less of an issue at higher levels, depending on how much Force is required for later abilities. And because there’s no auto-attack, a Monk Tank might run into a rage-starvation case where they can’t build aggro back up quickly because they’re low on Chi and don’t have enough Force to use an ability. Lots of time to see how it works out though.
On another note, I’ll admit I wasn’t very enthusiastic about Pandarens, but after listening to Chris Metzen and the rest talking about them, I’m willing to give this expansion a chance. I do love what I’ve seen of the setting and new areas so far though.