I don't own a windows phone and don't use any of these kind of apps, but doesn't the own existence of web site related apps represents a failure of said website to provide a decent web interface to mobile platforms?
I'm not referring in particular to hacker news or to this app, but websites in general that "need" a mobile app to properly or easily use it.
http://ihackernews.com/ is an excellent Hacker News mobile website. It also provides the third-party Hacker News API used by Combinator.
The problem is that Windows Phone doesn't allow users to pin website icons to their start screen (you can pin a static web page preview but it doesn't look very good). Fortunately, http://www.web2tile.com solves this issue, but not enough people are aware it exists. I may try to build a native app for it, but I'm not sure Microsoft would allow it.
I own a Windows Phone and I use ihackernews daily for browsing. web2tile looks interesting, though I seem to have a preference of not pinning websites (I just bookmark them).
I'm not referring in particular to hacker news or to this app, but websites in general that "need" a mobile app to properly or easily use it.