IPhone users love to search almost as much as they love their  iFart apps. Earlier this year, Google noted the iPhone drives 50 times the search queries of other mobile handsets. One wonders, then, what took Google so long in offering iPhone targeting through AdWords.

Now targeting is live, with a  great overview on the Google Mobile Blog. Can't figure out why you'd try it? There are 10 ideas below.

A few notes before we begin:

1)    Google refers to targeting "full HTML Internet browsers." That's more accurate than referring to this as iPhone targeting, but it's a mouthful. This new targeting will apply to an increasing number of handsets and already includes the G1 powered by Google Android.

2)    Consumers on the iPod Touch will also see these ads. Again, I'm oversimplifying below most of the time when referring to the "iPhone."

3)    The entries below aren't mutually exclusive. There's a good amount of overlap.

Now, let's go to the 10 reasons, maybe even the top 10 reasons, to run ads on full HTML Internet browsers.

1.  You're promoting an iPhone application. If you're developing an app specifically for iPhone users, then relevant queries can be an effective way to get the word out and jumpstart interest. It's not quite the same as targeting iPhone app ad networks, where you're targeting people who definitively use iPhone apps, but it's a potentially effective way to expand reach.

2. You're promoting a Google Android application. Medialets' Rana Sobhany recently noted in VentureBeat that there were fewer than 500 Android apps as of the end of November, well below expectations. This compares to over 10,000 iPhone apps that have been collectively downloaded over 300 million times. Right now, the iPhone's clearly where the app action is. It also makes me wonder if Google will allow ad targeting for specific devices and operating systems in the future, as many mobile ad networks do.

3. You're promoting an iPhone-optimized version of your site. If your site is designed for full-HTML mobile browsers, you can set those versions as landing pages.

4. Your site takes advantage of the phone's GPS. This could be one additional feature or it could be at the heart of the site's purpose. A retailer or quick-service restaurant, for example, could have a one-click store locator, and that might be a helpful differentiator for the search ad copy.

5.  A noticeable percentage of your visitors come from the iPhone. Your site analytics may be motivation enough to test ads targeting iPhone users.

6. You want to drive calls. Here, the creative can tie into the landing pages to make it easy to get consumers to call you rather than click around your site. It's not perfectly efficient; you'll reach some iPod Touch users in the process who can't call, so you don't want to make calling the only option -- but if calling will be better for both you and the consumer, give it a shot.

7. You're targeting early adopters. IPhone users are better-educated, wealthier, and have better hair than regular Web users (with the last one, I'm sure a joint iPhone-Hair Club for Men study will come soon). Want to reach them? Here's your chance to target them with something special.

8. You're a rigorous tester. How do iPhone-targeted ads on Google compare to its other mobile ads and PC Web ads? You could run with any benchmarks you can get your hands on, or you can run some tests to see the results for your own campaigns.

9. You want to impress Alexandra Kenin, Google's product marketing manager on the mobile ads team. She's featured in this how-to video, among others on the GoogleMobileBlog YouTube channel.

10. You want to tell your boss you're running ads on the iPhone. If you're already running AdWords, this is the easiest way to run iPhone ads. Take a screenshot of your ad running on the iPhone, make the boss happy, and then go back to doing whatever moves the needle for your business.