You may have gotten the marketing email from Navionics touting the launch of 2.0 for the iPhone. I had no intention of getting this but at $4.99 I couldn't resist. And I gotta say, it's fantastic. It emulates the Navionics Gold charts with all the POI data
including tides and currents. That was worth the five bucks right there as the free tide apps for the iPhone don't cut it for me. I already have a backup, portable GPS with all of the chart data, but having the charts and info on the device that's always on me will definitely come in handy (or let me kill time when away from the boat or a computer checking out various waterways). And as you would expect from the iPhone, if you tap on a POI like a marina and there is a phone number associated with it, you can dial directly from the app.
It seems to be a little buggy, occasionally quitting, but if you have an iPhone and want a cool, portable chart & marine info utility, it's totally worth the money IMHO.
Some screen shots:

(I have no connection to this product other than that I just bought it and I'm passing on my thoughts)