Been there, done that. :( I broke mine in 95 after a poor landing in the park.
Since then I always wear wrist guards. They are made by Dakine and fit under most gloves. They are a pain but better than a broken wrist again. Be aware, they won't prevent all hand/wrist injuries. I broke a bone in my right hand one time while wearing them. That was my own stupid fault though.
My sister actually broke her wrist from a standing position. She was waiting on someone, lost her balance forward on a steep slope and fell forward. Stuck her arm out and it broke. Season done.
At the area I patrol, wrist/forearm fractures are EASILY our most common injury amoung snowboarders. They really like it when you suggest they should maybe have been wearing wrist guards as you splint them up. :rolleyes: