They will be used this November.
Mississippi ordinarily doesn't hold legislative elections in even-numbered years. Actually they are every 4th year, since both house and senate members.
The constitution itself calls for apportionment every year ending in "2", plus whenever the legislature feels like it. Last year the legislature tried to reapportion in time for the 2011 elections, but failed to do so.
The NAACP sued in federal district court, but they ruled that it was not a violation of the US Constitution to have reapportionment only once every 10 years. This decision was affirmed by the US Supreme Court.
Reading the court's order, they retained jurisdiction; and said that if the legislature passed redistricting this year (2012) and this was approved by the USDOJ under Section 5 of the VRA, they would entertain claims that they should order special elections.
IOW, it is OK to reapportion every 10 years; but it might
not be OK to not use new district boundaries until another 3 years pass.
And if there are not lawful districts (*passed by the legislature; signed by the governor; and precleared by the USDOJ) the federal court could act to draw its own districts.
* Mississippi has its own backup commission consisting of the Chief Justice of the Supreme Court, the AG, the SOS, House speaker, and Senate president pro tempore in case the legislature doesn't finish its action.