For Web Directions South 2009 MOB developed a mobile experience called NOW to assist conference attendees quickly see which sessions were on (via topic track and time), who was tweeting and information about the speakers (including their twitter handles).
This was a bit of a trial to see if people would find an offering such as this useful. As such we targeted only iPhone users based on our knowledge of this audience's high browsing activity compared to other mobile device users. Our view was that if demand warranted, then for subsequent conferences we would also create the application for other device profiles.
The tweet stream was split into the 4 categories to align with the conference tracks - (and API provided by the guys at Agency Rainford from their Web Directions Tweeple application).
Based on the success of the application, MOB are now in the process of productising the NOW experience as a self-service set-up for conference organisers globally.
If you are interested in using this for your conference or event prior to commerical release then contact us for a chat.
You can check out Web Directions NOW on your iPhone at http://now.webdirections.org
Results
The conference had approximately 650 attendees and of the total attendees there were 450 unique iPhone users of the application. Over the 2 days of the conference there were over 12,000 unique page views or an average of 28 page views per user.
Interestingly there were only 19 other mobile operating platforms that accessed the application - most of those Android. Admittedly this may have been due to the target audience of the conference - predominantly people working hands-on in technology.

