After almost 2 years iDialog was updated to Version 2.0 a couple of days ago. iDialog is my preferred client for OCS/Lync at this point (at least until Microsoft finally releases their Lync client) – basically it is like Communicator but on your iPhone/iPad just without Audio/Video Conferencing capabilities.
But at least now it supports the iPad screen resolution This is a big step as the scaling before was an issue. Also finally support for Multitasking – even though the model chosen by the developers is let’s say interesting. The App will run for 9 minutes in the background – allowing for current conversations to finish. For these 9 minutes you’ll appear as Online to other users – after that the App shuts down. Unusual but interesting implementation – this way you can be sure your Battery will not be drained in the background.
There are some additional smaller features like emailing the contents of a conversation etc.
The update is available since May 18th. in the US App store, I am not sure about international availability. I recommend to update immediately – after Microsoft announced that the Lync Mobile Client will not be out until Q4 of this year this is still the best way to stay connected on your iPhone and iPad.