An ad-hoc app for Apple iOS devices is currently under development.
Anyway, the WebLite interface (see Web Client section) works fine on the iPad/iPhone Safari browser, so that's definitely a viable option for following the slides and participating in the Jabber room.
For what concerns audio, instead, you'll have to rely on one of the available standard streams: you can either attach to the RTSP feed we provide, or call the SIP URI associated with the room. This of course requires you to have a native client on your device supporting one of those protocols, and that such a client can also work in the background, since you'll need the browser in the foreground in order to effectively follow the meeting sessions.
As far as we know, the OPlayer app will receive streamed RTSP and can be configured to receive RTSP over UDP or TCP. User experience (thanks Scott for the feedback) is that it will run in the background while you use a web browser in the foreground.
Should you have any feedback about working RTSP or SIP apps, please feel free to drop us an email, and we'll put the info on this page.