At the INQ we have never signed an NDA, much to the annoyance of several companies. If we did, we certainly would not sign this one, which belongs to a secret society more than an IT outfit.
Firstly you are not allowed to mention the name Google without the approval of the company, nor can you write any articles about the NDA.
Google is allowed to disclose any information it likes under the NDA while the signer can only use the information only with the search engine's approval. So if Google tells its staff the sky is blue, then the staff can't use the same phrase when talking to their significant others.
The NDA says that Google does not want to be hearing about any confidential information that you might have and will not guarantee anything secret you might tell them.
We suggest that Google should go the whole hog and make people sign it in their own blood during a ritual involving the slaughter of half a dozen livestock.
Then the importance of never mentioning the name 'Google' will be really drummed home. You can read the whole NDA here. µ