Yes. It's done through a points system. You receive points for each incident you dispatch, although the number of points you receive seems dependent on the current mood of the IPN folks. There are a number of different rewards you can redeem points for - one of which is a month of free pager service (for 250 points, I believe).
I recently started using Incidentalerts.com after reading what folks had to say about it in other forums. There aren't many members so far and they nearly closed down the site last week. Apparently enough members complained about the close and they decided to keep it up and running. Sounds like they've had a significant increase in membership since then as well.
I think what they have going is a pretty neat idea. It's free, for starters. And they've incorporated Google Maps into the system so you can actually see an incident on the map. Definitely some room for improvement, but I like what they're doing.