On the eve of the 3G iPhone's launch, Apple opened its online App Store for iPhone and iPod Touch users. While the store didn't officially launch until today at noon EST, Apple users began downloading the free applications almost as soon as it went online early this morning. Apple prominently features a number of applications on its intro page, including online auction site eBay, mobile game Super Monkey Ball and location-based social networking app loopt.

loopt's CEO Sam Altman told Mobile Internet Trends in a recent interview that the loopt for iPhone app is free and the company plans to monetize the application by offering location-based ads, which will launch in about a month's time. While Altman wouldn't delve into the details of the LBS marketing plans, he said his personal loopt account already makes use of them. He noted that while some of the loopt employees found the ads a bit intrusive, he never has because the advertisements come with an incentive for the user. An ad for a nearby restaurant, for example, would include a coupon.

Yelp is now a partner with loopt to provide members a database of recommendations for points of interest, restaurants, bars and the like. loopt users can view Yelp reviews as well as the reviews of their loopt friends. This new feature puts Yelp and loopt squarely in competition with Pelago's Whrrl application, which has been characterized as Yelp meets LBS in the past. Altman said loopt users will soon be able to read the reviews written by all loopt users who opt-in in the next version of the application.

loopt is also launching loopt Link, which lets users sync their loopt account and activities up with any social networking application that makes use of RSS feeds (read: all of them.) loopt had a pre-exiting sync deal with Facebook, but now all other social networks can get loopt updates.

Finally, loopt is offering a feature called Meet in about two weeks. Meet will allow loopt users to get to know fellow users who are in the same vicinity. The impetus for Meet, according to Altman, was a church group who liked using loopt to stay in touch but would find it most valuable to get a notification when a fellow parishioner was nearby--even if they weren't already friends. Altman pointed to the popularity of LBS dating services in Asia that make use of the same idea as another reason for launching Meet, which will also allow users to filter based on age and gender.

loopt, however, is just one of many free LBS-centered services offered to iPhone users today: uLocate's WHERE applications and Pelago's Whrrl application are also available for download starting today. While the apps aren't all location-based, it seems the new 3G iPhone, now with GPS, will be the proving ground for the big winner of the location-based social networking race.

Poll: Last week we asked whether Virgin Mobile USA's decision to buy Helio was the right move. The vote was a 50/50 split with half our readers saying it was the right move and the other half saying it wasn't. This week's poll: Are you going to buy a 3G iPhone? Yes, I'll upgrade from the original. No, I'll never buy an iPhone. Yes, I didn't get the first one because I always wait for second generation Apple products. No, I like the original iPhone (and its rate plan) better.