The Huffington Post has launched its third local site, as expected, for Denver, Colorado.

An introduction from Ethan Axelrod, HuffPo’s Denver editor, explains the thinking behind launch in Denver and not another US city – namely the political importance of the state and Denver’s position as a destination for young professionals and businesses, he says.

The site is also planning launches of new technology, sport (end of October) and books (October 5) verticals – a move examined by the New York Observer:

“The advantage to adding verticals ad infinitum to general-interest websites is simple: they make it easy for web designers to mimic that familiar feeling of pulling out the business pages or flipping to the top sports story in traditional print newspapers. Drilling down on one topic at a time and carefully tailoring content by subject makes it easier for visitors to read what they want to and for advertisers to reach a specific, targeted audience,” the Observer reports.

Being able to roll-out new sections and topic pages quickly may suggest a landgrab approach towards attracting users.

As usability expert Jakob Nielsen tells the Observer, these sections allow sites to ‘scoop up’ users with specific interests and perhaps attract them to other parts of the site. To do this however, the content these sections offer must be more than just a filtering of the broader site.