So I found out today - from Mark himself - that Facebook has added the ability to access the site via a HTTP Secure (HTTPS) connection (like Twitter already does). This will drastically increase security for Facebook users.
Basically, HTTPS provides a combination of the HTTP and SSL protocols, which enables encrypted communication between your computer and a web server (THIS IS GOOD). Without it you’re exposed to significantly more security vulnerabilities, especially if you're using a public Wi-Fi to access Facebook. If you're at Starbucks hanging out on their public Wi-Fi network, someone using Firesheep can easily get onto your Facebook account and steal your data. HTTPS makes it a lot harder to do that. On public Wi-Fi networks you should only enter private information (passwords, phone numbers, credit cards numbers) to sites accessible via HTTPS, if at all.
The feature is available as an option on the "Account Settings" page. Click "Account Security," then check the "Secure Browsing (https)" box. If you have Twitter, do the same there.