Redistricting is the process of creating or changing district boundaries for congress, for a state legislature or for local elected offices.
Every 10 years after the U.S. census is taken, the seats in the House of Representatives are reapportioned among the states based on population. The 2010 census numbers are out. See the Census Bureau widget (Apportionment tab) to see which states gained or lost seats. Each state has its own process for drawing the boundaries; some are fairly non-partisan; others highly partisan.
Check out Daily Kos Elections for a lot of good information on political races around the country. You can find a lot of diaries on redistricting, including many where people have used my redistricting app (see below).
Check out Maps for some files of redistricting plans that can be loaded in Dave's Redistricting App.
|June 2011 proposal from CA Redistricting Commission
using Dave' Redistricting App