I seem to remember some Louisiana gaffers complaining that the general would often just wind up as two republicans.
That's because they have a jungle primary and have a run-off later, it's not instant.
Instant run-off is where you rank your choices and if no one clears 50, the top two gather votes from the lesser candidates. It would look something like this:
1 Ralph Nader
2 Al Gore
3 George Bush
After all the votes are tallied, it's found that Gore and Bush were the two top vote-getters, so they move into the next round. But since Nader didn't, your vote gets counted for your next viable preference, Gore.
Basically this is designed so that if you're not truly satisfied with either of the party choices, you won't have to worry about "throwing your vote away" and this might encourage more people to vote third party rather than holding their nose or whatever. Several states already have run-off elections (Georgia for example has regular primaries, but if neither candidate clears 50 they hold a runoff election later just between the top two). I'm not a huge fan of the jungle primary system just because a race between two Republicans or two Democrats sucks for people of the opposing side, but if it came with IRV I wouldn't be too upset.
