About Mac Encryption
FileVault 2 is Apple's full-disk encryption solution for Mac computers. Since the entire disk is encrypted, you're forced to enter your username and password on boot (before anything else can be loaded) to decrypt the disk. That's why Automatic Login is unavailable when using FileVault 2.
This level of security has the unfortunate side effect of preventing you from remotely rebooting a FileVault 2-encrypted Mac, since you're unable to connect to the Mac using SSL or Screen Sharing.
Using the FileVault Configuration Tool
Apple's solution is to use the FileVault configuration tool fdesetup with the authrestart command. It asks for your username and password BEFORE the Mac is rebooted, stores these credentials in memory, reboots the Mac, and supplies those credentials to FileVault 2, allowing the Mac to be remotely rebooted without the boot-up login screen.
To use fdesetup, open the Terminal app and execute the following command. Be careful though, as it will cause an immediate reboot of the system (as though you used the shutdown command):
sudo fdesetup authrestart
After the reboot, your hard drive will be unlocked and you will be presented with the standard MacOS Login Screen.
Not every Mac supports this command though. To find out if yours does, you can execute this command:
fdesetup supportsauthrestart
If the response is true, then you're ready to reboot.
Not a Perfect Solution
If your encrypted Mac has a kernel panic or power failure, and a reboot is forced, you won't be able to use this tip and will need a pair of remote hands to manually enter your credentials if you're not using some type of remote KVM Switch.