Yes, the android App is on the way, graphs are all complete, hoping to test soon ..
What's the benefit of an App over the new Mobile site?
Kind of like do you prefer vanilla or caramel?

Mobile: The mobile App uses less bandwidth
The App's render the graphs on the phone, rather than download. The average weather page view is about 200-400kb, which is usually no drama on most mega-gigabyte ADSL plans. But mobile data is different & can be limited/expensive. Each weather refresh on the mobile uses about 20kb (about a 10th), or
Mobile is easy & fast .. tap the icon, and custom native hires graphs are displayed
Mobile has a fully native iphone experience to use the classifieds, including uploading piccies direct from camera
Mobile doesn't completely cover the site .. e.g. No forums, or weather extras, photos etc..

.. it's focussed on the Weather & Buy & Sell at this stage...
Hope that helps.