agora is available on the AppStore since January 2012.
agora is available on the Android Market for devices with at least Android-2.0. Note that the agora-release.apk is also available from the download area.
On a Mac, download and unzip the agora.app.zip, then click on the agora icon (or do : open agora.app, from a terminal). Remember that data files are searched within the directory :
~/Documents/agora