As the blog of the National Council of State Legislatures, The Thicket, notes:
In addition to who controls the legislature, and policy-setting, for the next four years in these states, these elections are interesting for two other big reasons. They set the table for the 2010 redistricting cycle. In fact, legislators elected in Louisiana, Mississippi and Virginia this year will draw the legislative plans used in the 2011 elections for these states. New Jersey has a commission system for redistricting.
For example, as Seth McLaughlin of the Washington Times writes, “one of the few certainties after the [Virginia] elections is that Republicans will no longer have complete control of drawing district lines.”
FYI, the NCSL website provides a 2007 Election Wrap-Up.