In a nutshell:
- Emblems of Triumph and Emblems of Frost will be converted into Justice Points.
- All PvE emblems and badges below Frost and Triumph will be converted into gold. This even includes legacy badges, like Badges of Justice.
- Arena Points, Honor Points, any leftover Battleground Marks of Honor, Stone Keeper's Shards, Venture Coins, and Spirit Shards will be converted into the new Honor Points.
- Rated Arenas and Rated Battlegrounds won't be available again until Season 9 (shortly after the release of Cataclysm), when they can be entered to win the higher-tier PvP Conquest Points.
Someone asked how much gold per badge, and it was figured out to be 3.75g per badge.