You can enable this by going to Settings > Email & Mobile. It is the new top setting. There is a preview available so you can see what the mobile template will look like. I have only just started playing with it but it seems the only widget you get is the 'about me' widget. So if, like me, you have widgets for Twitter feeds and links to other blogs then these do not display.
A while ago I made an app for this blog (Post here) to make my posts more easily readable on android devices. These new templates from Google have the advantage of being usable on all devices as well as needing no design flair or HTML knowledge.
Will you be applying them or do you prefer people to see the full web version of your blog?