I can ensure you we never ban sites for using someone else's search results. That would be silly and would only hurt our comprehensivenes and search quality in the end.
In fact, Infospace uses results from Overture, Inktomi, FAST and Altavista so they are not considered competition.
If there is a penalty in effect which I cannot confirm without knowing the URL it must be for some other reason such as overoptimization. We place penalties on sites whose sites are using techniques that are designed to make the results show up at inappropriate times and in inappropriate placements within the search results and thereby hurting the user experience.