Hotlist iPhone appLocation-based service The Hotlist aggregates Facebook and Twitter feeds to tell its users where the hottest spots in town are – as defined by where their friends are going. The service was solely available online for the past year. But now it’s launching an iPhone app and plans to deliver Blackberry and Android apps shortly.

The idea of The Hotlist is to show users where their contacts from social networks are congregating, or have visited in the past, or are going to in the future. The Hotlist gives users information on Facebook events, which show who’s invited to an event (such as a birthday party or a concert) and who’s going. That way users are not only on top of what’s trending now, or where friends have frequented in the past, but can plan ahead when looking for things to do with friends.

The service also pulls in data from Google and restaurant review service Yelp to show what’s going on around the vicinity of users or around the world.

The Hotlist boasts around 130,000-140,000 active users, says Chris Mirabile, president and co-founder of the company. “But we expect to attract much more people now that the iPhone version is out, and the other mobile versions coming out soon, because mobile is really where a service like this is truly useful.”

The company is a team of five people and is looking to hire two more developers in the next couple of weeks. It plans to make money like many other location-based services — through deals with venues, going hyper-local, and offering businesses a way to bring in the pundits. The New York-based company was founded in September 2009 and scored $800,000 in funding this May from angel investors, led by Joe Grano’s Centurion Holdings. The Hotlist originally won a grant of $25,000 from NYU Stern Business Plan Competition, and is a part of 160 Varick Street Incubator in New York City.