It is still early days with the Trezor support.
We are writing a separate library (so that other teams can use it) called trezorj.
To see progress you can watch that project and see the commits going into it.
It is here:
https://github.com/bitcoin-solutions/trezorjBecause open source projects tend to be done in people's spare time it is difficult to say when things will actually be finished.
Also, there is quite a lot of testing etc that needs to be done for something like Trezor.
A typical usage, once you have the device setup, will be:
1) Start up MultiBit, say you already have 2 wallets open in there.
2) You plug in your Trezor - a third wallet then appears. This syncs and you can see the balance and transactions on your Trezor wallet.
3) When you want to spend you create the spend as normal in MultiBit but for it to actually get signed and sent it:
a) Gets sent to your Trezor
b) On the Trezor screen you see the recipient Bitcoin address and the amount.
c) Using the Trezor buttons you either approve it or cancel it.
d) The signed transaction gets sent back to MultiBit, which then broadcasts it to the Bitcoin network.
There are extra features like having a PIN and one-time-passwords but that is the basic usage.
Edit: Trezor supports both hierarchical deterministic (HD) wallets - which MultiBit will use - and also Electrum deterministic wallets.
I believe both Electrum and Armory plan to support Trezor so there should be a choice in the wallet software you use. I don't know where the other teams are in their coding.
