You probably don't remember signing up for Facebook, but the process underwent a significant change recently. Google is no longer allowing the direct importing of Google contacts in Facebook by Facebook users, citing what it claims is Facebook's unfair data protectionism.
In Google's API Terms of Service, the document outlining the conditions under which third parties can access Google's services in an automated way, Google demands that any third party accessing data on behalf of users must itself have a method for users to withdraw this data. Google is upset because Facebook does not do this with the e-mail addresses it retrieves. Of course, Facebook isn't interested in your Google e-mail addresses outside using them as an identifying token to find your friends.
Google is claiming that their terms of service act in the best interest of users and data, going so far as to set up a provocatively named "Trap my contacts now" page which outlines Google's objections to Facebook's importing policy and displaying it when a contact export is attempted. Google states that "once you import your data there, you won't be able to get it out." While this is true of the e-mail addresses of other people, all of the data relating to you on Facebook is retrievable. Any user of Facebook can-- from their account settings-- download a catalogue of all their time wasted on Facebook. This exported data does not include the e-mail addresses imported by Facebook to find your Facebook-using friends, and this makes sense. Facebook is not an e-mail program. All addresses imported from Google will be available from Google.
In March 2009 a bat flew into the external fuel tank of the space shuttle Discovery, injuring its wing. The bat clung onto the fuel tank as Discovery launched, causing its death. Thousands mournfully joined the R.I.P. Space Bat Facebook group. If Facebook complied with Google's terms, the administrators of this group would have access to thousands of e-mail addresses. It makes sense for Facebook to be willing to regurgitate my personal data upon request, but Google's request requires that they be able to provide the data of others, which is absurd.
Either Google is unaware of the purpose of the contact-import-- to find your friends-- or they're intentionally misleading users.