Earlier quoted context omitted.
It does send your IP address to Google, when you download the filter. And I can't tell if "Enhanced Protection" is enabled which actually sends your URLs to Google.
http://kb.mozillazine.org/Browser.safebrowsing.remoteLookups That's configured here
upd: I am searching for it in the Firefox sources now. Just for curiosity: there are 117512 files in 8610 directories totaling 743 MB, and search in files is really slow even on SSD.