Jeb tweeted an image of what appears to be potion durations. There’s three empty bottles in his inventory that further supports this theory.
They seem to be pretty self-explanitory… speed is likely increased movement speed, strength is likely the damage done to mobs (and it’d be awesome if it sped up block-breaking), jump would be an increased jump height, resistance would probably be reduced damage taken, and water breathing is obviously the ability to not drown or slow down the rate at which your character runs out of air.
We’re not sure if they all have multiple tiers of potions like the Speed II and Strength II. We’re also not sure if it’s a stronger potion or if it’s just two speed potions drank back-to-back. Also unclear is the starting duration of the potions (at least 6:34 seconds) or what the ingredients are.
Unfortunately in his tweet he said that this will not likely make the 1.9 Adventure Update patch. Also, Notch has stated that 1.9 will likely get item repairing! Sweet!!