As Errol noted in a previous thread, the New Zealand government has announced the schedule for public consultation on whether the country should retain its mixed-member proportional (MMP) electoral system.
Somewhat mirroring the process of double referenda that led to MMP’s adoption in 1992-3, there will be an initial referendum with the questions, “do you want a change from MMP?” and “if changed, what to?” This will be concurrent with the 2011 general election.
Then, if a majority say they prefer not to retain MMP at the first referendum, there will be a second referendum on MMP vs. the leading alternative identified by the first one. This second referendum would happen with the 2014 general election.
The alternatives and exact question wording are still being developed. Will the alternative to be pitted against MMP be chosen by plurality? That could have some perverse outcomes and incentives, if there is not a consensus on the best alternative (as there was when MMP was pitted against other alternatives to FPTP in 1992). NZ uses ranked-choice ballots (with STV) at some local elections, and one or more of the alternatives is likely to be one of ranked-choice ballots. So why not use AV to choose the electoral system?