A list of resources on the effect of pair-work, especially about pair programming is available on the c2 wiki pair programming page especially the pair programming benefits. A fun and brief introduction to benefits, perils and simplicity of pair programming can be found in an early paper on the subject Everything I learned about pair programming I learnt in kindergarten by Laurie Williams and Robert Kessler, University of Utah 1999.
Starting Pair Programming and observing what happens when team members pair program is very useful as an indicator for how well the team members really work together. Interpersonal conflicts can no longer remain hidden, and if the FiveFreedoms are not well in place, arguments and friction will surface quickly. Also, slacking and hiding a lack of skills are no longer possible. That said, many people are unjustly afraid of 'being unmasked' - they have more skills than they realize.