Dual boot Linux and Lion on FileVault 2 disk
Installing rEFInd and following the included instructions does work for me using OS X 10.8 with FileVault2 and Debian GNU/Linux using grub-efi.

In short: Use a protective MBR and install rEFInd to the efi system partition (esp) (use rEFInd's install.sh --esp). Rename the refind folder on the esp to BOOT and rename the efi file aswell to allow faster loading of rEFInd.

In Debian mount the esp, create a subdirectory debian in /efi/EFI, load the efivars kernel module and install grub-efi.

Make sure you read also the general instruction on that page regarding installation.