What is the 'Mac OS X Base System' disk image on my 2011 MacBook AIr?

Question

On my 2011 MacBook Air with Mac OS X Lion, I boot into Recovery mode via holding the command-R key during startup, if I go into Terminal and do a diskutil list, I get a list of 12(!) logical disks. disk0 is of course the disk holding the main HD and the Recovery HD partitions (along with the GUID partition and the EFI partition). But there is also a disk1 with partitions including one titled Mac OS X Base System that is approximately 1.39 GB big. There also are 10 other disks of varying but small sizes.

What are these other logical disks (and partitions) and is there any way to reclaim their space?

Update: Here is a copy of the diskutil list output:

[]