According to the description it looks like it will be pretty useful if you are attending a VMUG:
Attending a VMUG User Conference. Download the event app before you go to have all of your conference details at your fingertips. The app will provide you with real-time updates on sessions, speakers, exhibitors, and networking opportunities. You’ll be able to take notes, follow Tweets, connect with other attendees, provide session feedback, and more, all from your phone. Enhance your VMUG experience by utilizing the VMUG User Conferences mobile app!
It looks like it is worthwhile downloading it prior to attending the event, since it’s around 20MB, so that you are not competing for conference bandwidth.