Mounting a "Mac OS Extended (Journaled, Encrypted)" drive formatted in Lion on either Mac OS X Leopard or CentOS 6
Unfortunately, Apple introduced a new technology called Core Storage to handle the new full disk encryption.  You can read about it in John Siracusa's review of OS X Lion.  This new type of volume cannot be read yet by other OS versions, but I'm sure some third party will eventually create some software that will enable reading these volumes on other operating systems.