A couple of months ago AT&T release a beta version of their VPN Client for linux.
Unfortunately they released the client as a RPM ( RedHat package ) and not
as an Ubuntu DEB package.
But help was nearby, on this website I found how to convert the RPM
package to an Ubuntu DEB package.
And here you can download the latest IBM AT&T VPN Client
for Linux (@ 07/01/09 )
Internet -> AT&T Global Network Client
And check it out AT&T VPN client on Linux