Google has uploaded a video of a 30-minute talk from Google Engage For Agencies, about making mobile-friendly websites.
Google's Shane Cassells discusses four benefits of the mobile web over apps: easier to find (through search, blogs, Twitter and links in emails), increased market size (impressions and clicks higher on mobile web than apps. anyone has access to your site), lower development costs (creating a mobile site vs. developing a mobile app), and it's easier to maintain (if changes are made, you don't need to upgrade because all users see is the newest version).
Make no mistake. Google wants you to build good mobile sites. You might say it makes it easier for Google to index mobile content. Late last year, Google introduced the GoMo resource site to help sites get mobile.
The site has a "GoMoMeter" to test your site. It shows you how your site looks on a smartphone, and provides a free report with personalized recommendations. All you have to do is enter your URL.
It also has a list of services you can use to get your site started, which you can view by service type, annual cost and timeframe. There are also various guides for agencies, advertisers and publishers.