Whrrl, a cross between Loopt and Yelp with a bit of Zvents thrown in, is vying in an increasingly competitive and noisy "mobile social" or "LBS" space for attention. Today the company (Pelago is the company behind Whrrl) announced a deal with Maponics for better neighborhood data. The company also buys similar data from Urban Mapping. 

In no particular order, other competing services in the US include BrightKite, Where/uLocate, mobile Yelp, Citysearch, Loopt, Buzzd, GoodRec, Socialight and others. As they evolve, Facebook, MySpace, Bebo and Twitter are competitors as well. Conventional search engines are also competitors as local information sources. For example, Google aggregates reviews and Google Maps offers location finding, etc. 

There may be one or two mobile-centric breakouts in this segment but the online "brands" have a big head start and a certain gravitational force. For the mobile startups, having right mix of content and functionality, as well as the money to survive and outlast rivals, will be critical. 

Better neighborhood data will offer some incremental help, but what Whrrl needs is usage first and foremost to build momentum. It's efforts to leverage Facebook and Twitter are a step in the right direction.