Update - 03.31.2010
I decided that I didn't like the accuracy of the location from the browser. It is isn't as good as the MapKit or default Google Maps app on the phone. I added a button the directions page to open default maps application.
One of the best features used in Google Maps is the turn-by-turn directions. Unfortunately, I haven't seen, and don't even know if it exists without proprietary code, an effective way to show turn-by-turn directions using the MapKit API in the iPhone SDK. Though Google announced that they have included it in their Android platform they were vague about if/when it might come to the iPhone SDK. No matter, where there is CoreLocation there is a way.
Most smaller companies only have one "brick and mortar" location. So I wanted to show that location on the map and then present the user with ability to get turn by turn directions to their location. In my example app the marker will show the location of my favorite sushi place in Memphis, Sekisui's Pacific Rim
No clear way to implement turn-by-turn directions with MapKit using the iPhone SDK. Though Safari for the iPhone has the ability to get your current location via the browser, i wasn't very impressed with it's accuracy.
Use CoreLocation to get the user's lat/long and then pass that to a UIWebView that will display a Google Map with directions. Though in this example I am using a local html that is stored on the phone a better implementation would be to have the file stored remotely and then cached on the user's phone for faster load time. However, it is important to note that you should "decache" the file if the user's previous coordinates are different then their new current location.
For the best results and accuracy it is better to run this on your device since CoreLocation the simulate will show Apple's headquarters as the user's location.