Shavings or pellets? For a caged bunny? Free run? Outdoors or indoors?
Cedar and to a lesser extent pine is considered bad for small animals because the same odor that makes it smell good will also cause internal issues: ie: studies show that male rabbits exposed to cedar shavings are much more prone to not wake up from anesthetic after a neuter.
Wood stove pellets are pine but they'reusually treated so they don't have the same toxic properties. Ditto with some horse stall pellets.
If you're only using them in the litter box and the bunny isn't living/sleeping in them (free run bunnies) or they're in very well ventilated areas (outdoors), it's not much of a problem.
Just to add, wood pellets are kiln dried which removes the dangerous chemicals. You can also get kiln dried pine shavings, although since shavings hardly absorb anything anyway you'd be much better off with wood pellets.