You can download Babbel for one of the following platforms:

Mac OS X 10.2 and up
PowerPC native
(Snow Leopard compatible)
Download
Mac OS X 10.4 and up
Intel native
(Snow Leopard compatible)
Download
Windows NT/2K/XP/VistaDownload
 
Current version: Public Alpha 100106.10
Read the release notes to see what was changed.