Mac OS X Lion 10.7.0 Substitue "Recovery HD"

terminal output

$ diskutil list

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *250.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh_HD            249.2 GB   disk0s2
   3:                 Apple_Boot                         650.0 MB   disk0s5

$ diskutil eraseVolume HFS+ Blank /dev/disk0s5

Started erase on disk0s5
Unmounting disk
Erasing
Initialized /dev/rdisk0s5 as a 620 MB HFS Plus volume
Mounting disk
Finished erase on disk0s5 Blank

$ diskutil list

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *250.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh_HD            249.2 GB   disk0s2
   3:                  Apple_HFS Blank                   650.0 MB   disk0s5

$ diskutil mergePartitions HFS+ Macintosh_HD disk0s2 disk0s5

The chosen disk supports resize; disregarding your new file system type and volume name
Merging partitions into a new partition
     Start partition: disk0s2 Macintosh_HD
     Finish partition: disk0s5 Blank
Started partitioning on disk0
Merging partitions
Waiting for the disks to reappear
Growing disk
Finished partitioning on disk0
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *250.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh_HD            249.7 GB   disk0s2

$ diskutil cs list

No CoreStorage logical volume groups found

$ diskutil cs convert disk0s2 -passphrase mysecret

Started CoreStorage operation on disk0s2 Macintosh_HD
Resizing disk to fit Core Storage headers
Creating Core Storage Logical Volume Group
Attempting to unmount disk0s2
Switching disk0s2 to Core Storage
Couldn't unmount disk0s2; converted volume won't appear until it's unmounted
Core Storage LVG UUID: 53E2A042-7A1A-4964-9621-0E82E7F02D76
Core Storage PV UUID: A66721E5-0EF9-432A-A52E-A13540EFF008
Core Storage LV UUID: 185BA4C9-15D3-4D59-9C54-F783A70D23DD
Finished CoreStorage operation on disk0s2 Macintosh_HD
Encryption in progress; use `diskutil coreStorage list` for status

$ diskutil cs list

CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 53E2A042-7A1A-4964-9621-0E82E7F02D76
    =========================================================
    Name:         Macintosh_HD
    Sequence:     1
    Free Space:   0 B (0 B)
    |
    +-< Physical Volume A66721E5-0EF9-432A-A52E-A13540EFF008
        ----------------------------------------------------
        Index:    0
        Disk:     disk0s2
        Status:   Online
        Size:     249715376128 B (249.7 GB)

$ diskutil list/dev/disk0

   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *250.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:          Apple_CoreStorage Macintosh_HD            249.7 GB   disk0s2
   3:                 Apple_Boot Boot OS X               134.2 MB   disk0s3