I commuted home Thursday in the same 50 mph gusts as Velobambina, and it wasn't fun. It didn't seem exceptionally dangerous, but it was exhausting, especially since I was riding into sustained 25-30 mph+ headwinds. I didn't ride my bike to work yesterday when the winds were just as strong but the temperature was about 15 degrees colder.

I'd say about 20 mph is the highest I'd venture out into willingly for recreational riding. But when it's time to go home from work, just about anything is doable.