There’s a blog post stating that there is already an app:
There is an actively used API, on top of which NewsBlur’s users have built a mobile website, an Android app, a Windows Phone app, and a Nokia MeeGo app.
I can find one paid Windows Phone app stating support for Newsblur, but I don’t know whether that is any good. It’s called “feed me”.
Still waiting for this to make decision too, especially because Newsblur is not a free service.
The ability to have apps for Newsblur in both Windows PC and smartphone become the decisive factor because if there’s only apps for one, there’s no point using such service over the stand alone RSS apps.
Feedly already has at least NextGen supporting both Windows RT and Windows Phone.
I am using Feed Me (“feedme” in store) with Windows Phone. Works very well and syncs with NewsBlur. Actually my favourite way of accessing RSS feeds now.
There is an app called MetroBlur for Windows Phone that I use. It doesn’t have the best interface in the world but it works.
MetroBlur is Windows Phone 8 only.
I really don’t like Feed Me comparing to NextGen or Fuse, it looks so much unusable.