Seems like Facebook doesn't turn on SPDY for all its CDNs yet. I only see SPDY turned on for sphotos-a.xx.fbcdn.net and photos-a.xx.fbcdn.net, which only serve a rather small portion of all the static assets. The lion share of its assets are mainly served through fbstatic-a.akamaihd.net, fbcdn-photos-a.akamaihd.net and other *.akamaihd.net domains, which aren't SPDY-enabled currently.