Rabbit Nose

Many people don't know this, but almost 90% of a rabbits breathing is done purely through their nose.

That being said, this is why it's so dangerous when a rabbit gets the sniffles.

If they mainly breath through their nose, and their nose gets all stuffed up, you're going to end up with a very sick bunny.

Now, when a rabbit wiggles it's nose, this is body language.  Because their nose is wiggling, doesn't mean they are breathing quickly.  Just like if their nose isn't wiggling, this doesn't mean they have stopped breathing either.

Basically, the more relaxed a bunny is, the more it's nose will wiggle.  A terrified rabbit almost never wiggles it's nose.

Often times, people have their rabbits indoors with them.  A relaxed bunny may watch you doing something.  As they become more interested in what you're doing, their nose wiggling may increase. Along with this action, they will probably raise one ear in their curiosity.

Now sometimes, your rabbit will be wiggling their nose, then suddenly stop.  This could be they suddenly feel frightened, confused, unsure, or maybe they're just so happy, they've even past the point of wiggling their nose :)