Foursquare announced that Foursquare 3.0 – the latest version of its app (for Android and iPhone) will be available tonight. One very significant new feature of this is a discovery tool called “Explore”.

“The idea is pretty simple: tell us what you’re looking for and we’ll help you find something nearby,” explains CEO Dennis Crowley. “The suggestions are based on a little bit of everything – the places you’ve been, the places your friends have visited, your loyalty to your favorite places, the categories and types of places you gravitate towards, what’s popular with other users, the day of the week, places with great tips, the time of day, and so on. We’ll even tell you why we think you should visit a certain place (e.g. popular with friends, similar to your favorite spots). You’ll find it’s helpful for general things like ‘food’, ‘coffee’, ‘nightlife’ (we built in quick access to these searches) and you’ll be surprised by what you get when searching for really specific things, like ’80s music,’ ‘fireplaces,’ ‘pancakes,’ ‘bratwurst,’ and ‘romantic.’ The more random you get, the more interesting the results get (though be patient with this first release…sometimes we can’t find every random thing).”

The app also incorporates some of this into the “Me” tab, with regards to recommendations. Crowley says this helps you find guidance from friends on categories they’ve explored the most.

“You’ll see that we’ve replaced our old leaderboard (and its simple points system and Sunday night reset) with a sliding 7-day barometer of you and your friends,” Crowley says of another new feature. “Check-ins now trigger points for dozens of different types of actions – everything from discovering new places, trying new types of restaurants, visiting new cities, getting groups together, hanging out with old friends, and a few things you might not expect.”

If you’re a business owner, you’re probably most interested in how the new Foursquare can help you get and keep customers. Foursquare will be launching six new types of specials that merchants can offer later this week (presumably at SXSW). With these, Crowley says businesses will be able to offer specials to swarms, groups of friends, regulars, newbies, mayors, or everyone.

On the Places screen in the Foursqure app, users will see a list of all the Specials nearby.

Crowley recently hinted that Foursquare would have some major offerings coming at SXSW that would be key in competing with Facebook Places. While Facebook still has the advantage of having 600 million users, this should be a good start.

Foursquare also entered a deal with American Express, which should help too.

The new app will be available for other platforms like BlackBerry, Windows Phone 7, and  Symbian eventually. BlackBerry users can expect a new app this week, but without all of the frills of this one.

I’ll leave you with some tweets from the Fousquare team…