For those of you that bank with them, Their apps are now available within the store, although apparently the RBS one only works in scotland. I have no account with either, so I can't test.
Just waiting for the other High street banks to get onboard now!
NZ's ASB has had an app for quite a while now, its a decent one too and ammusingly had the iTrinket users complaining that they wanted the newer cleaner interface in their app, till they figured out which app it was they were coverting
I've had the Natwest one on WP for about a week now (they had a big PR thing on Facebook about it) and its great, and I prefer it over the Android one they have so well worth grabbing
RBS one works well.
Only irritation is paying the Natwest Credit Card with them isn't as easy as I would like compared to full online banking.