Without being rude, you should already know what user data is as part of your site evaluation. Any owner of a site on the web should be constantly looking at user data found on site servers.
The site server should have an administrative program telling you what searches are being used to reach the site, better known as "search strings." The program should also be telling you how many pages the user looks at on each visit and where in the site they go. By reviewing these statistics, you can identify the sections of your site that appeal to potential customers. If clients are leaving after visiting only one or two pages, such statistics should tell you that you have an abandonment problem. The new information from the Google patent should motivate you to closely monitor your site.
Essentially, Google is also looking at your server statistics to determine the value of your content and factoring it into the rankings. Specifically, Google claims in the patent application that it tracks the amount of time that users spend accessing a page on your site. Having filed a few patent applications in my time, what this really means is Google is looking at how long a user spends on your site and how "deep" they go into it.
Expanding on this subject, Google details an additional factor. As with the Adwords program, Google is monitoring the click through rate on search results. The more click-throughs to your site from its listings in Google, the higher it will be moved in the search results.
Google claims that it looks at what users are bookmarking. The apparent jist is that Google considers a site with a lot of bookmarks to be "worthy" of a higher ranking. In short, get out there and bookmark your sites!
The effort of Google to look for depth in a site should be commended. There is nothing worse then clicking onto a promising search result to find one crappy page full of links. With this new policy, Google rewards sites with healthy amounts of relevant pages. In short, content is king again.