Apple Insider posted a story that Apple on Monday released Lion Recovery Disk Assistant software to enable users to create recovery partitions on external drives.
Creating an external Lion Recovery using the assistant requires that the Mac already have an existing Recovery HD. The external drive must also have at least 1GB of free space, while Lion Recovery Disk Assistant is a 1.07MB download.Apple issues Lion Recovery Disk Assistant for external drives
The new partition will not be visible in the Finder or Disk Utility on Mac OS X, but can be accessed by rebooting the Mac while holding the Option key.