Call me crazy, but I still prefer ASR for disk cloning. It's simple and accurate. But ASR in Lion no longer allows file-level cloning. This means that block copying is now the only option. Block copying is great, but it requires the unmounting of both disks. This means that cloning a boot drive while booted from that drive is no longer possible in Lion.
This Lion-specific problem has a Lion-specific solution: boot from the Recovery Partition. Despite the fact that Lion's ASR has been inexplicably hobbled, the Recovery Partition is quite full featured and provides many SysAdmin-friendly tools, including a full featured Terminal and ASR command.
Running ASR from the Recovery Partition allows you to unmount and, thus, block copy your boot partition without reaching for an external boot drive or DVD.