Building and optimizing a site for the "mobile Web" is a lot more difficult than doing so for the PC. You've got a conventional HTML site, which may not work if it's flash-heavy. Then you've got apps, which publishers and brands may or may not need, and then you should have a "touch-friendly" iPhone-optimized mobile site. 

Most sites are not well designed for the mobile Web and many marketers are simply unaware of how critical this is becoming. Gomez, in a self-serving way, has documented that poor mobile performance can affect sales and have a negative impact on brand impression. 

Mobile browser Taptu now has released a report that analyzes the degree to which sites are set up and optimized for what it calls the "touch Web" -- basically for smartphones with touchscreens. The company examined 113 million sites and found that roughly a third were "touch-friendly." 

By category, here's Taptu's breakdown of the percentages of sites that are touch-friendly:

Taptu defines "higher quality sites" as those "which as used as the basis of our category-level analysis are defined as those with above average quality score for either visual quality or information quality."

The shopping sites are best positioned, with social networks not far behind. Mostly that means Facebook, MySpace and Twitter. Facebook is very well set up for mobile of course, across devices and platforms. What's a bit surprising is how poorly configured the "places, travel & local" category is. Only 9% of "higher quality" sites in the category are optimized for touchscreen smartphones. Yet this is content heavily used by mobile subscribers with data plans. 

Over the next 12 months every major brand and publisher will need to upgrade for smartphone owners.