SSL is more processor intensive as well as uses slightly more bandwidth. Not sure if this is why it hasn't been implemented on a lot of websites but you can definitely use it with facebook.

As others have suggested, a private VPN session or an SSH tunnel will work. I use VyprVPN by Giganews whenever I'm in a public hotspot. Ultimately there's no true solution for privacy as everything can be broken down - including a wired connection. Anyone that's used wireshark could've been able to see all this data that Firesheep is showing - Firesheep just makes it that much easier and requires less tech knowledge than wireshark (at least that's what I'm assuming seeing as it's getting this much publicity.)

Want to protect yourself? Don't use a hotspot you don't trust. Don't use a hotspot that doesn't employ any form of encryption. Use a VPN session, SSH tunnel or at the very least SSL websites. Don't know if your website supports ssl? change the "http://" to "https://" and see if it loads. If it does, you're in business, if not see option #1 or #2.

Security's my thing!