I finally got my Cisco Firewall Security Specialist cert after finishing the FIREWALL (642-618) exam a couple of months ago. I noticed that Cisco Specialist cert is good for 2 years not unlike the 640-xxx Associate or 642-xxx Professional level certs, which are valid for 3 years.
I started studying for VPN (642-648) but also recently found out that Cisco revised their CCNP Security track and retiring the Security Specialist certs. So I got until April 2014 to finish VPN and get my ASA Specialist cert (combination of FIREWALL and VPN certs).
I put some screenshots taken from Cisco's website since the URL sometimes changes or becomes unavailable later on.
I was able to confirm with the folks from Cisco Learning Network (CLN) that my SECURE, FIREWALL, VPN and SITCS will qualify me to become CCNP Security certified. Here's the CCNP Security certification exam migration path.