[Galaxy S II Original Android Development] cowbutt:
WARNING!

In the light of today's (20120807) news:

"there’s an issue with some temporary CWM.zip files floating around that can also cause these hard bricks. XDA Elite Recognized Developer Entropy512, who has been on the forefront of preventing further damage to users’ devices, has managed to find the specific problem. There is a string in the binary that’s been shown to be dangerous, and moderators are working currently to get it off of XDA thanks to Entropy512. This only appears to affect the Touch version of the temporary CWM, and no issues have been reported with the standard version."

http://www.xda-developers.com/android/temporary-cwm-zip-on-galaxy-note-found-as-a-cause-of-hard-bricks/

However...

$ wget http://download2.clockworkmod.com/recoveries/recovery-clockwork-touch-5.8.1.5-galaxys2.zip
--2012-08-07 15:05:57-- http://download2.clockworkmod.com/recoveries/recovery-clockwork-touch-5.8.1.5-galaxys2.zip
Resolving download2.clockworkmod.com... 173.192.187.130, 50.23.163.121
Connecting to download2.clockworkmod.com|173.192.187.130|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1587023 (1.5M)
Saving to: `recovery-clockwork-touch-5.8.1.5-galaxys2.zip'

100%[======================================>] 1,587,023 636K/s in 2.4s

2012-08-07 15:06:00 (636 KB/s) - `recovery-clockwork-touch-5.8.1.5-galaxys2.zip' saved [1587023/1587023]

$ mkdir recovery-clockwork-touch-5.8.1.5-galaxys2
$ cd recovery-clockwork-touch-5.8.1.5-galaxys2/
$ unzip ../recovery-clockwork-touch-5.8.1.5-galaxys2.zip
Archive: ../recovery-clockwork-touch-5.8.1.5-galaxys2.zip
signed by SignApk
inflating: META-INF/MANIFEST.MF
inflating: META-INF/CERT.SF
inflating: META-INF/CERT.RSA
inflating: META-INF/com/google/android/update-binary
inflating: META-INF/com/google/android/updater-script
inflating: etc/recovery.fstab
inflating: res/images/icon_clockwork.png
inflating: res/images/icon_error.png
inflating: res/images/icon_firmware_error.png
extracting: res/images/icon_firmware_install.png
inflating: res/images/icon_installing.png
extracting: res/images/icon_installing_overlay01.png
extracting: res/images/icon_installing_overlay02.png
extracting: res/images/icon_installing_overlay03.png
extracting: res/images/icon_installing_overlay04.png
extracting: res/images/icon_installing_overlay05.png
extracting: res/images/icon_installing_overlay06.png
extracting: res/images/icon_installing_overlay07.png
extracting: res/images/indeterminate01.png
extracting: res/images/indeterminate02.png
extracting: res/images/indeterminate03.png
extracting: res/images/indeterminate04.png
extracting: res/images/indeterminate05.png
extracting: res/images/indeterminate06.png
inflating: res/images/progress_empty.png
extracting: res/images/progress_fill.png
inflating: res/keys
inflating: sbin/adbd
inflating: sbin/e2fsck
inflating: sbin/fix_permissions
inflating: sbin/killrecovery.sh
inflating: sbin/mke2fs
inflating: sbin/nandroid-md5.sh
inflating: sbin/parted
inflating: sbin/recovery
inflating: sbin/sdparted
inflating: sbin/tune2fs
$ strings META-INF/com/google/android/update-binary | grep -i "mmc\|discard"
warning: %s: Discard failed
warning: %s: Wipe via secure discard failed, used discard instead
emmc
/proc/emmc
/dev/block/mmc
/dev/block/mmcblk0
EMMC
EMMC:
failed to open emmc partition "%s": %s

Would appear to suggest that the recommended method (method 1) is unsafe if combined with a handset containing a defective eMMC device and running a kernel that passes through MMC_CAP_ERASE commands (e.g. kernels included in recent official stock Samsung 4.0.4 ROMs).