I have two house rabbits and two cats. They all get on fantastically, I've had house bunnies for 10 years or so, and only recently got the cats - they'll be 1 yr old in a week. We deliberately got kittens so that they would grow up being used to the bunnies and learn from the start how they should act with them. We introduced them v gradually, and very sensibly, and now they're friends. They snuggle together, infact one bunny and one cat are currently sat in the bunnies cardboard box, both fast asleep. If either felt threatened then that just wouldn't happen. The cats lick the bunnies, and they often drink out of the water bowls together.
I think if introductions are done right then different species can get on harmoniously, although it does also depend on the personalities or breed of the cat/dog. For me the bunnies comes first as they've been here the longest, but I know them well enough to know if they are even the tiniest bit scared.
Eddie cat and Lavender bunny.
Buxton cat and Darwin bunny.
All four fluffies: