OMG grow up, you use google every day, you have facebook, twitter and maps on your phone but suddenly you worry because the developer of brew who needs some metrics! The only thing missing now is the Snowden guy to make a blog post about it.
As echoed by many others above, I never gave Homebrew consent to send any information to Google; it should be opt-in. Frankly, I was quite annoyed after updating Homebrew and found it already trying to connect to Google Analytics immediately after. Thankfully, I was able to block the request with Little Snitch and then opt-out of the analytics, but it certainly left a bad taste in my mouth that they’d start collecting data before even letting me opt-out first!