We have expected that 64-bit version of this operating system will be now called native one, and that 32-bit one will be pushed back as a legacy product, and this happened. So, if you download a non-marked "Beta 3 Edition", you are getting a 64-bit version.
The versions available for download are Standard Edition, Enterprise Edition, Datacenter Edition, Web Server and version for computers equipped with Intel Itanic processors. Langunanges are English, German and Japanese, and if you don't like downloading, several versions will be available on a separate DVD. µ
See Also
Longhorn becomes Windows Server 2007
L'INQ
Microsoft web-site for
downloading Longhorn beta software