It is, and they LOVE it. They sit out there and munch all day, of course I only take them out for a few hrs at a time on nice, sunny days.
The bunnies however don't seem to like it outside, they just "freeze" and don't do much of anything. Hubby is going to build them a nice big enclosure, with a top of course and hopefully they get used to it out there.
I would never trust any of them outside at night time, but it's sure nice to get them out throughout the day for some sunshine!