If anyone wants to check I got a Level 2 integration working in production of google checkout-zc-1.4.5 and zencart-1.3.7.1 at http://isooz.com

Took me a few days to set it up, but the longest I had to wait was for the webhosting company http://www.webcity.com.au to install the SSL certificate, they were a little slow.

Luis