Those results are from google.com. The Brazilian TLD for Google is google.com.br. I just did a quick search on both now and for the .com TLD I got 52.7% vs 47.3% for Rousseff, and for the .com.br TLD 54% vs 46%. Official polls run by several different media agencies were giving Rousseff with 60%+ of valid votes.
On the first turn of our major elections, when we voted for Senators, Governors and Congressmen, something similar happened. For my state a certain Senator candidate had 17% on previous public surveys and it was ranking 3rd. After the results were out he was elected with 36% and he was the 1st.
Here in Brazil such surveys and predictions are quite dangerous, to some extent they are used as manipulative tools. Most people are unfortunately uneducated and ignorant in issues concerning politics and economy and those people are likely to vote on the candidate which seems to be winning, just so they don't "lose" their vote (yes, this is not an uncommon reasoning around here, insane as it may sound). Worst of all perhaps is the fact that we are obliged to vote, it is an imposed duty. Our democracy is still an infant, and I think we are yet to reach adolescence. Some rough years to come.