With the iPhone OS 3.0 announcement that Apple’s new iPhone software update will include Google Maps integration, you can expect an explosion of location-based apps to start appearing in the App Store. There are already a few location-based apps available now, including ones we’ve written about before — Job Compass and Locly, for instance. Here are five more that are worth a look.

uSonar (Free)

There are lots of apps available that let you keep up with your social networks while you’re on the go, but what about when you’re bored and want to find someone local to hang with? uSonar lets you know who’s around and what they’re up to, whether they are someone you already know or not. Members post “blips” about their activities and locations, then you can message them directly through your iPhone or iPod touch. Everything about uSonar is opt-in, so you’re in control of who can see where you are, or send you a message or email. You can even post anonymously if you’d like.

Loopt (Free)

If you want people outside your immediate location to be able to find you, try Loopt. This app lets you broadcast your whereabouts or send pictures to everyone in your social networks, like Twitter and Facebook. It works across all major mobile phone carriers and supports over 100 different models of phones so your buddies without iPhones can find you. It also integrates nicely with the review Web site Yelp, so if you’re stumped on ways to spend your Saturday afternoon, you can find something to do.

Hear Planet (Free)

If you like to go sightseeing when you travel, then you’ll love Hear Planet. It uses geolocation to determine where you are, then feeds you tons of information about the area’s landmarks, famous buildings, historical sites, and more via your headphones. More than just an audio tour guide, listen while you drive around running errands and you just might learn something you never knew about your hometown.

Whrrl (Free)

Some folks love micro-blogging so much that they want to document every minute of their day. If that’s your thing, let Whrrl help. Use your iPhone’s camera to snap pictures of your lunch, trip to the market, and visit to the dentist, uploading to Whrrl as you go. You can even add text and messages if you choose. Your location and micro-stories are shown on a map, which is really neat if you happen to be around other Whrrl users doing the same thing as you. Imagine attending the Super Bowl and updating the experience as it happens, while simultaneously watching someone else across the stadium do the same. Cool. If any of this sounds familiar, it’s a lot like Brightkite.)

Traffic ($1.99)

This app will let you know what the traffic conditions are like in your area and display them in list form or superimposed on a map. Traffic gives you details on how severe the traffic situations are — is there a 4-alarm fire with road blockage on Main Street, or a small fender bender with a slowdown due to rubbernecking? The app automatically locates where you are, but you can enter the location of your choice so you can get traffic conditions anywhere.