A systems analyst is a person who know about the computer application area and enough software development to draw a master plan for a computer system.
As an analogy, a systems analyst is somewhat like the combination of an architect and a civil engineer. The architect side talks to the client who wants a structure built in a certain way. The architect translates the wishes of a client to a drawing and design blueprint. The civil engineer side evaluates the cost and feasibility of a structure based on the design and blueprint.
In the building industry, an architect is different from a civil engineer. This means that an (inexperienced) architect can draw up a design that cannot be built. However, a systems analyst needs to assess the feasibility of a system in addition to designing it to begin with.
The key function of a systems analyst is to make sure the team is on the same page. This begins with well prepared documents of the system. These documents are equivalent to blueprints of a structure, laying out walls, pillar, struts, pipes, faucets, electrical boxes, switches and etc.
The blueprint of a system, once approved, is shared amongst the whole team.
The job outlook of systems analyst is quite good. A growth of 29% is expected from 2006 to 2016 (http://www.bls.gov/oco/ocos287.htm).