Currently the preferred mobile strategy at Oxygen Software is responsive websign, where your mainpage will adapt the the device that is viewing it. If you for some reason should have a project where you wont be using response webdesign, but make a dedicated mobile site instead, jQuery mobile might be a worth a look.
Its a easy to use framework to use, to make your webpages look like mobile apps.
Official site: http://jquerymobile.com/
IKEAs mobile site: http://m.ikea.com/