A couple of points.
- First, this is perception of being informed, not actual knowledge. Perceived knowledge and actual knowledge are positively correlated, but not perfectly so, and there are segments of the population who believe they are better informed than they actually are, and the consumption of certain media can exacerbate this effect (i.e., talk radio). Here respondents were asked not whether they are better informed thanks to the Internet, but rather whether others are better informed. That's a subtle difference.
- There's an interesting table on the types of information available on the net that makes you feel better informed. Look at it (Q34 on the raw questionnaire, but page 2 of the pdf). In most cases people feel better informed, but the fascinating failure, if you will, is for "civic life and government activities in your community," a 49-49 split. Also the net seems to better serve national and international news as opposed to local news (see top of table). That makes sense, as the Internet destroys geography and cobbles us back together based on interests, partisanship, and the rest.