UK bank Barclays has confirmed on Twitter that a Windows Phone app is currently in development. The only issue is that they have the end of the year as the deadline, which makes us assume they're very early in the development stage, aren't pouring much time and effort into it, or aren't making any promises (likely number 3). At least the bank has looked at Windows Phone as a viable platform to support.
@rhyshancock Hi Rhys, thanks for your tweet. We're pleased to confirm we're planning to release a Windows app by the end of the year. ^JC— Barclays UK (@BarclaysOnline) February 28, 2013
Barclays will join the Royal Bank of Scotland (as well as Natwest) who also supports Windows Phone. We'd like to see the remaining establishments to also show signs of an app in development, but this is a strong signal that the platform is starting to be viewed by large brands as one with enough users to warrant an app to be developed.