My wife and I never experienced jealousy since we've figured out we are and should be polly. I have some insecurity issues with her and guys, although that's been swept under the rug from what our experiences tell us.
She's never really had jealousy, it just doesn't exist for her, which is really weird for others looking in.
I know a woman who really loves to explore poly relationships, but for the longest time was really jealous of her lover and his exploits.
I think the jealousy thing is natural and common, but it comes down to what will you do with it when you feel it? Her enjoyment is more important than the nervousness a male makes me feel. With that in mind, I remember that, I can breathe easy, it's not important.