The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Mobinett Interactive:
4G World App powered by Plug from Mobinett Interactive is an engaging location-based Mobile application for 4G World 2011. Quickly sign up with LinkedIn or Facebook accounts to find 4G World events, information on exhibitors and to network with people of interest. App shows you the list of your contacts from LinkedIn, Facebook and Plug attending the event and automatically matches you with new people based on interests, profile and mutual connections on social media. Using Meeting maker, setup meetings with people you want to know. You can follow all the Twitter activity, Reply, RT and view Twitter profiles. App also offers several features using which you can get up-to-date agenda, maps/directions, take instant polls, post comments to the event wall, Twitter, Facebook and LinkedIn right from the App.