Transit planner HopStop launched its free iPhone application last week to rival the mobile version of Google Map’s Transit option. The application, with support from iPhone’s GPS functionality, offers all the same services as the website. This includes trip customization, maps marked with nearby subways and bus stops, a taxi mode that estimates time and cost of travel and contact information for taxi companies, and the ability to re-route a transit plan that is provided.

In the past, Hopstop was ahead of competitor Google Transit in terms of providing transit info for a widespread amount of metropolitan areas but Google has caught up (and maybe surpassed) with its Maps-based transit planner. And Google Maps is integrated with iPhone 3G’s GPS, making Google Transit a free native application that doesn’t have to be downloaded.

The first reviews posted on the iPhones apps store were fairly positive. Let us know what you think of the HopStop app in comments. Is it better than Google Transit on the iPhone?