I'm with Cigarick,
Some of the people who responded to this post saying "Search the previous posts" were just plain rude about it!
Of course, you can search, but sometimes its easier to post a question than to have to trudge your way through ten thousand posts that all have "cellophane" in the title or body.
Plus, it gets people talking, which is the great thing about forums, and it lets us all share our knowledge, our experiences, and learn from others.
Now, about the subject. I usually leave the cello on, to protect them when I carry them around and to just not have to fool with it...but then again, I haven't been a brother of the leaf for too long, so I haven't gotten to age very many of mine yet. If I age them, I'll probably remove the cello, though most sources I've seen have said leaving it on or off doesn't make that much a difference in aging.