Like Google Web Accelerator, the Google Secure Access client is no longer available to the public. Unfortunately, it is now restricted to only some Mountain View hotspots.
I really liked the concept and I hope it will become available once again in the future. It looks like vpn.google.com still resolves, however when trying to connect to the service nothing happens.
It really made me feel more secure when surfing by knowing that any data I was sending over the network was secure, https or not. Please bring it back!