All,
We've now got a fix for the "User Rate Limit Exceeded. Please sign up" error. The problem was that the build was making calls to the API even with a primed cache.
You need to do the following in your dev environment:
1. Clear the cache using: rm -rf _tmp
2. Build the site as normal using: rake clean preview
3. If you hit the "User Rate Limit Exceeded. Please sign up" error, then try:
3.1 Disconnect from the VPN and rebuild
4. Once the site builds successfully, you will have a primed cache, and subsequent builds won't make any Google Book API calls.
Going forward, you should be able to clear your cache when required. It's unlikely that we'll exceed the API limits now that the build isn't making excessive calls.