A mobile version would be great! As a Windows Phone user, I wasn't expecting an app in the first place. Microsoft really needs to bring more content to the app store.
I hope MS sticks it out with Windows Phone, even though I don't see how they can make it long term competing against an OS that is given away for free and has already sucked up the developers and customer base that Apple hasn't claimed. I was a phone store recently for the first time in years and was really digging the 'Metro' UI. If you have an Xbox you can see the same design aesthetic has been introduced over the past couple of years. While I think the OS and platform is inferior, from a design and aesthetic standpoint, it is probably my favorite OS above iOS and definitely above Android. Sadly, I think the ability to bring more content to the app store is largely out of their hands. They have a terrible chicken and egg scenario where they need developers but they won't come unless there are customers, but there are no customers because there are no developers making enough high quality apps. They need to grow, but how do compete against free (Android) and unequivocal quality (iOS)? Tough...
If there ever is an API, I'll try my hand at making a Windows Phone app. I have made a few and know how much it sucks to be left behind when it comes to apps.