I haven't, but Mario Batali was talking about it on his show during the past week
I missed the beginning of it, but he was talking about using all of the fennel in a dish - how it adds layers of flavor. The pollen was used as a condiment - dusted over the dish before serving.
Someone was telling me about getting it for Christmas and that she really enjoyed it. It's new to
me, but I did some googling. There seem to be different sources for it, the best being from wild fennel in Italy and it's very expensive, but not much is needed. Here's a link to an article by John Thorne I found on the net, gives a pretty good overview. The Spice House sells the California-grown variety.